Close

Develop and maintain backend services and APIs with a focus on AI-powered CRM features. | Senior engineer with experience in backend development, API design, and working with AI technologies. | About Us Since 2013, we've been building a CRM that gets out of your way and helps your team sell more, faster. Now we're building AI into every part of it, so Close does the busywork and your team does the selling. No manual data entry, no 10-click workflows. Just communication-first, AI-powered sales software designed to help you succeed and scale. We're bootstrapped and profitable which means we answer to our customers and play by our rules. We're proud of our 120-person, 100% remote team, focused on building Close so that no small, scaling business fails because it can't figure out sales. Our Stack Our backend tech stack consists primarily of Python Flask web apps with our TaskTiger scheduler handling many of the backend asynchronous task processing chores. Our data stores include MongoDB, PostgreSQL, Elasticsearch, and Redis. The underlying infrastructure runs on AWS using a combination of managed services like EKS, MSK, RDS and ElastiCache and non-managed services running on EC2 instances. We have CI/CD pipelines that build Docker images, run automated tests and deploy to Kubernetes clusters. We also use these images in our local development environment allowing coding locally against all of our services. We have a well-documented public API that is consumed by our front-end JavaScript app as well as numerous integrations. Our infrastructure is heavily automated using Terraform, Ansible and other AWS tools. We love open sourcing our code and ideas on our GitHub and on The Making of Close, our behind-the-scenes Product & Engineering blog. Check out our open source projects like SocketShark, TaskTiger, LimitLion and ciso8601. AI is both how we build and what we ship, and that's reshaped what engineering looks like. This is a transformation we're embracing and find deeply exciting. Our Teams When you apply, you'll have an opportunity to highlight the team that appeals to you the most. We'll do our best to honor this preference, but we'll also be evaluating skillset fit and the needs of the business. One thing to know up front: we do move people between teams as the work shifts. Most engineers here end up on more than one team over their time at Close - this team is where you'll start, but over time you'll likely have the opportunity to work on many different projects. The work splits roughly like this. Pick the team that excites you most: • Agents. Build Close's agentic platform and customer-facing AI experiences. Voice Agents, Custom Agents, and Ask Chloe are already in flight. You'd work on the shared intelligence and orchestration layer that powers AI-driven processes across the product. That includes the ecosystem around our APIs and MCP surface, which enables external agents like Claude and ChatGPT to operate Close. This team is pushing deeper into applied AI, retrieval, and agent infrastructure more than ever before. • Communications. Own the voice, SMS, and email infrastructure powering Close - Twilio, WebRTC, WebSockets, AssemblyAI, ElevenLabs, and more. You'll help build our voice, messaging, and conversational AI agents while scaling real-time AI across calls, email, and calendar sync infrastructure. • CRM. Build the structured context layer that humans and agents both depend on. We're rebuilding the data model so it flexes with real businesses, making the CRM agent-ready (retrieval, traversal, action coverage through MCP and our public API), and shipping the next generation of AI-native CRM features (AI Enrich, Autofill, AI Search). Operating on billions of Mongo documents with Elasticsearch underneath. • Growth. Run the experiments and own the billing infrastructure that turn trials into paid customers. Stripe metered billing, AI credit top-ups, the activation and conversion funnel, and the team's biggest bet right now: agentic onboarding (an agent that walks new customers through setup, configuration, and first comms). Hypothesis-driven, metric-first. You Are • A seasoned engineer. Python is our backbone, but perhaps you've worked across Go, Rust, or TypeScript. You pick the right tool for the problem rather than retreating to what you know. You've seen a variety of problems, can collaborate and self-direct. • Building AI. You've shipped LLM-backed features for real users and have a POV on where they're trustworthy, where they fall over, and how to get them production-ready when customers bet revenue on the output. We use Pydantic, Temporal, LangFuse, and other modern AI infrastructure tooling to power our agent platform. • Working with AI in your day-to-day. You use AI tools in your own workflow to ship faster, write tighter code, and reason about unfamiliar parts of the codebase. We fund the use of AI tools (Claude Code, Codex and other best-in-class developer tools) and treat learning and experimentation as part of the work. • A builder first. You'd rather get the first iteration of a feature in front of fifty customers than spend three weeks fretting over a perfect PR. You ship. • Opinionated about API design for modern software. You've shipped internet-facing APIs and you think about who's on the other end - apps, agents, humans poking around in docs - and what each of them needs. • Battle-tested. You've debugged incidents where latency budgets didn't hold, owned a system everyone else relied on, or carried a pager for something with real customer impact. Benefits • Compensation: Competitive pay plus an organization-wide goal-based bonus • Paid Time Off: ~5 weeks of PTO to start. Plus a 1-week all-company Winter Holiday Break and paid US holidays. You'll earn 2 extra days for every year you're with Close. • 80% Work Option: Work with your manager to choose between a standard 5-day week or a 4-day week at 80% pay • Parental Leave: Paid leave for primary and secondary caregivers • Sabbatical: A 1-month paid sabbatical every 5 years with the team • Healthcare (US residents): Two medical plans with Close covering 99% of your premium, plus Dental, Vision, HSA, FSA, and company-paid Long-Term Disability • 401k (US residents): We match your contributions up to 6%, vested immediately Our Values Build a house you want to live in - Examine long-term thinking and action No BS - Practice transparency and honesty, especially when it's hard Invest in each other - Build successful relationships with your coworkers and customers Discipline equals freedom - Keep your word to yourself and others Strive for greatness - Constantly challenge yourself and others Learn More Listen to our CEO and Founder, Steli Efti, tell the story of Close's journey in the $0-30m Blueprint. Watch our culture video from our 2023 team retreat in Milan. Every year our entire team gathers in person to build connection, foster cross-functional collaboration, and have fun. In 2027, we're headed to Dusseldorf, Germany! Explore our product. Check out a demo! Our Hiring Process We ask a few role-specific questions as part of our application process. These questions are designed to help us learn more about you from the start, so please answer each one thoughtfully. We see this as an opportunity to get to know you beyond your resume. We use AI tools daily at Close and expect candidates to do the same. In evaluating your application, we aim to get a sense for you - the way you think, how you communicate, the work you've done. Applications that read as fully AI-generated will not be considered. Regardless of fit, you can expect to hear back from our team with an update on the status of your candidacy. If you progress to the interview process, you'll receive a full outline of the role-specific steps in your first touchpoint with us. We do our best to make the hiring process clear and human.

Build and maintain AI-powered internal tools and systems to improve support workflows and customer experience. | 3+ years software engineering experience, strong coding skills in relevant languages, systems thinking, AI fluency, and excellent communication in a remote environment. | About Us Since 2013, we've been building a CRM that gets out of your way and helps your team sell more, faster. Now we're building AI into every part of it, so Close does the busywork and your team does the selling. No manual data entry, no 10-click workflows. Just communication-first, AI-powered sales software designed to help you succeed and scale. We're bootstrapped and profitable which means we answer to our customers and play by our rules. We're proud of our 120-person, 100% remote team, focused on building Close so that no small, scaling business fails because it can't figure out sales. About the Role We're hiring a Software Engineer to build the tools and AI Systems that our Support team runs on. Support is one of the things our customers love most about Close, and as ticket volume grows and AI rewrites what good support looks like, we're adding another embedded engineer inside the Support function to continue building the systems that make our team great and keep our customers happy. AI runs through everything we're building here. This person will be tasked with deciding what parts of the support workflow to automate and what to leave alone, then shipping those decisions. You'll work directly with the Support team and our other Support Engineers, so you know what's most valuable to build and have close technical collaborators. You'll report to our Director of Support. You Are • A Software Engineer who builds for the person sitting next to you. You have 3+ years of Software Engineering experience and can write clean, production-quality code. You're drawn to problems where you can watch a Support Rep get faster and more effective within a few days of shipping. You're excited by the idea of a tight, collaborative feedback loop. • Backed by a degree or experiences in the sciences. You have a degree or rigorous experience in Computer Science, Mathematics, Physics, Electrical or Mechanical Engineering. This shows up in how you reason through systems and approach problems. • Technically deep. You're fluent in Python, Rust, Go, or Typescript/Javascript. You have built information retrieval systems using semantic search / RAG. • A systems thinker. When you see a manual process, you have an unignorable itch to fix it. You think about upstream and downstream consequences before you commit. • AI-fluent, not AI-dependent. You use Claude, Codex, Pi, or whatever makes you faster. You also understand what the code is doing, can debug it when it breaks, and know when to set the tools down and think from first principles. • A clear, async communicator. You write well. Your technical specs are readable, your PRs are well-documented, and your Slack messages don't create more questions than they answer. You thrive in a fully remote, async-first environment. • Comfortable with autonomy. You scope your own work, manage your own priorities, and don't need heavy oversight to ship. You're pragmatic over theoretical and have a strong bias toward action. • Located in US time zones. (ET, CT, MT, or PT) You Will • Build internal tools that scale Support. Design and ship the systems that Support Engineers and Support Reps rely on daily - AI drafting tools, autonomous reply systems, workflow automation, reporting dashboards, and anything else that removes friction from the support operation. • Own projects end to end. You're the engineer who takes "this part of the workflow is painful" to "this part of the workflow doesn't exist anymore." No PM intermediary, no thrown-over-the-wall requirements. You work closely with the Support team to understand what to build, then you build it. • Ship customer-facing tools when they take work off the queue. You'll build self-service migration scripts and diagnostic tools customers can run themselves instead of opening a ticket. • Collaborate closely with Support. Reps and Engineers are your primary users and your best source of requirements. You're embedded enough that you see what's actually broken before anyone files a ticket. • Improve the systems underneath the work. Better abstractions, more reliable integrations across Close, Stripe, Twilio, and the rest of the stack. What you build today becomes infrastructure the team builds on tomorrow. • Experiment and ship. The team has real latitude to try new approaches. If there's a better way to do something, you're encouraged to prototype it, measure it, and ship it! Benefits • Compensation: Competitive pay plus an organization-wide goal-based bonus • Paid Time Off: ~5 weeks of PTO to start. Plus a 1-week all-company Winter Holiday Break and paid US holidays. You'll earn 2 extra days for every year you're with Close. • Parental Leave: Paid leave for primary and secondary caregivers • Sabbatical: A 1-month paid sabbatical every 5 years with the team • Healthcare (US residents): Two medical plans with Close covering 99% of your premium, plus Dental, Vision, HSA, FSA, and company-paid Long-Term Disability • 401k (US residents): We match your contributions up to 6%, vested immediately Our Values Build a house you want to live in - Examine long-term thinking and action No BS - Practice transparency and honesty, especially when it's hard Invest in each other - Build successful relationships with your coworkers and customers Discipline equals freedom - Keep your word to yourself and others Strive for greatness - Constantly challenge yourself and others Learn More Listen to our CEO and Founder, Steli Efti, tell the story of Close's journey in the $0-30m Blueprint. Watch our culture video from our 2023 team retreat in Milan. Every year our entire team gathers in person to build connection, foster cross-functional collaboration, and have fun. In 2027, we're headed to Dusseldorf, Germany! Explore our product. Check out a demo! Our Hiring Process We ask a few role-specific questions as part of our application process. These questions are designed to help us learn more about you from the start, so please answer each one thoughtfully. We see this as an opportunity to get to know you beyond your resume. We use AI tools daily at Close and expect candidates to do the same. In evaluating your application, we aim to get a sense for you - the way you think, how you communicate, the work you've done. Applications that read as fully AI-generated will not be considered. Regardless of fit, you can expect to hear back from our team with an update on the status of your candidacy. If you progress to the interview process, you'll receive a full outline of the role-specific steps in your first touchpoint with us. We do our best to make the hiring process clear and human.

Build and own internal AI-powered support tools and systems to improve support team efficiency and customer experience. | 3+ years software engineering experience, technical fluency in Python, Rust, Go, or JavaScript/TypeScript, strong systems thinking, AI fluency, excellent async communication, and US time zone location. | About Us Since 2013, we've been building a CRM that gets out of your way and helps your team sell more, faster. Now we're building AI into every part of it, so Close does the busywork and your team does the selling. No manual data entry, no 10-click workflows. Just communication-first, AI-powered sales software designed to help you succeed and scale. We're bootstrapped and profitable which means we answer to our customers and play by our rules. We're proud of our 120-person, 100% remote team, focused on building Close so that no small, scaling business fails because it can't figure out sales. About the Role We're hiring a Software Engineer to build the tools and AI Systems that our Support team runs on. Support is one of the things our customers love most about Close, and as ticket volume grows and AI rewrites what good support looks like, we're adding another embedded engineer inside the Support function to continue building the systems that make our team great and keep our customers happy. AI runs through everything we're building here. This person will be tasked with deciding what parts of the support workflow to automate and what to leave alone, then shipping those decisions. You'll work directly with the Support team and our other Support Engineers, so you know what's most valuable to build and have close technical collaborators. You'll report to our Director of Support. You Are • A Software Engineer who builds for the person sitting next to you. You have 3+ years of Software Engineering experience and can write clean, production-quality code. You're drawn to problems where you can watch a Support Rep get faster and more effective within a few days of shipping. You're excited by the idea of a tight, collaborative feedback loop. • Backed by a degree or experiences in the sciences. You have a degree or rigorous experience in Computer Science, Mathematics, Physics, Electrical or Mechanical Engineering. This shows up in how you reason through systems and approach problems. • Technically deep. You're fluent in Python, Rust, Go, or Typescript/Javascript. You have built information retrieval systems using semantic search / RAG. • A systems thinker. When you see a manual process, you have an unignorable itch to fix it. You think about upstream and downstream consequences before you commit. • AI-fluent, not AI-dependent. You use Claude, Codex, Pi, or whatever makes you faster. You also understand what the code is doing, can debug it when it breaks, and know when to set the tools down and think from first principles. • A clear, async communicator. You write well. Your technical specs are readable, your PRs are well-documented, and your Slack messages don't create more questions than they answer. You thrive in a fully remote, async-first environment. • Comfortable with autonomy. You scope your own work, manage your own priorities, and don't need heavy oversight to ship. You're pragmatic over theoretical and have a strong bias toward action. • Located in US time zones. (ET, CT, MT, or PT) You Will • Build internal tools that scale Support. Design and ship the systems that Support Engineers and Support Reps rely on daily - AI drafting tools, autonomous reply systems, workflow automation, reporting dashboards, and anything else that removes friction from the support operation. • Own projects end to end. You're the engineer who takes "this part of the workflow is painful" to "this part of the workflow doesn't exist anymore." No PM intermediary, no thrown-over-the-wall requirements. You work closely with the Support team to understand what to build, then you build it. • Ship customer-facing tools when they take work off the queue. You'll build self-service migration scripts and diagnostic tools customers can run themselves instead of opening a ticket. • Collaborate closely with Support. Reps and Engineers are your primary users and your best source of requirements. You're embedded enough that you see what's actually broken before anyone files a ticket. • Improve the systems underneath the work. Better abstractions, more reliable integrations across Close, Stripe, Twilio, and the rest of the stack. What you build today becomes infrastructure the team builds on tomorrow. • Experiment and ship. The team has real latitude to try new approaches. If there's a better way to do something, you're encouraged to prototype it, measure it, and ship it! Benefits • Compensation: Competitive pay plus an organization-wide goal-based bonus • Paid Time Off: ~5 weeks of PTO to start. Plus a 1-week all-company Winter Holiday Break and paid US holidays. You'll earn 2 extra days for every year you're with Close. • Parental Leave: Paid leave for primary and secondary caregivers • Sabbatical: A 1-month paid sabbatical every 5 years with the team • Healthcare (US residents): Two medical plans with Close covering 99% of your premium, plus Dental, Vision, HSA, FSA, and company-paid Long-Term Disability • 401k (US residents): We match your contributions up to 6%, vested immediately Our Values Build a house you want to live in - Examine long-term thinking and action No BS - Practice transparency and honesty, especially when it's hard Invest in each other - Build successful relationships with your coworkers and customers Discipline equals freedom - Keep your word to yourself and others Strive for greatness - Constantly challenge yourself and others Learn More Listen to our CEO and Founder, Steli Efti, tell the story of Close's journey in the $0-30m Blueprint. Watch our culture video from our 2023 team retreat in Milan. Every year our entire team gathers in person to build connection, foster cross-functional collaboration, and have fun. In 2027, we're headed to Dusseldorf, Germany! Explore our product. Check out a demo! Our Hiring Process We ask a few role-specific questions as part of our application process. These questions are designed to help us learn more about you from the start, so please answer each one thoughtfully. We see this as an opportunity to get to know you beyond your resume. We use AI tools daily at Close and expect candidates to do the same. In evaluating your application, we aim to get a sense for you - the way you think, how you communicate, the work you've done. Applications that read as fully AI-generated will not be considered. Regardless of fit, you can expect to hear back from our team with an update on the status of your candidacy. If you progress to the interview process, you'll receive a full outline of the role-specific steps in your first touchpoint with us. We do our best to make the hiring process clear and human.

Build and maintain AI-powered internal tools and systems to improve support workflows and customer experience. | 3+ years software engineering experience, strong technical skills in relevant languages, systems thinking, AI fluency, excellent async communication, and US time zone location. | About Us Since 2013, we've been building a CRM that gets out of your way and helps your team sell more, faster. Now we're building AI into every part of it, so Close does the busywork and your team does the selling. No manual data entry, no 10-click workflows. Just communication-first, AI-powered sales software designed to help you succeed and scale. We're bootstrapped and profitable which means we answer to our customers and play by our rules. We're proud of our 120-person, 100% remote team, focused on building Close so that no small, scaling business fails because it can't figure out sales. About the Role We're hiring a Software Engineer to build the tools and AI Systems that our Support team runs on. Support is one of the things our customers love most about Close, and as ticket volume grows and AI rewrites what good support looks like, we're adding another embedded engineer inside the Support function to continue building the systems that make our team great and keep our customers happy. AI runs through everything we're building here. This person will be tasked with deciding what parts of the support workflow to automate and what to leave alone, then shipping those decisions. You'll work directly with the Support team and our other Support Engineers, so you know what's most valuable to build and have close technical collaborators. You'll report to our Director of Support. You Are • A Software Engineer who builds for the person sitting next to you. You have 3+ years of Software Engineering experience and can write clean, production-quality code. You're drawn to problems where you can watch a Support Rep get faster and more effective within a few days of shipping. You're excited by the idea of a tight, collaborative feedback loop. • Backed by a degree or experiences in the sciences. You have a degree or rigorous experience in Computer Science, Mathematics, Physics, Electrical or Mechanical Engineering. This shows up in how you reason through systems and approach problems. • Technically deep. You're fluent in Python, Rust, Go, or Typescript/Javascript. You have built information retrieval systems using semantic search / RAG. • A systems thinker. When you see a manual process, you have an unignorable itch to fix it. You think about upstream and downstream consequences before you commit. • AI-fluent, not AI-dependent. You use Claude, Codex, Pi, or whatever makes you faster. You also understand what the code is doing, can debug it when it breaks, and know when to set the tools down and think from first principles. • A clear, async communicator. You write well. Your technical specs are readable, your PRs are well-documented, and your Slack messages don't create more questions than they answer. You thrive in a fully remote, async-first environment. • Comfortable with autonomy. You scope your own work, manage your own priorities, and don't need heavy oversight to ship. You're pragmatic over theoretical and have a strong bias toward action. • Located in US time zones. (ET, CT, MT, or PT) You Will • Build internal tools that scale Support. Design and ship the systems that Support Engineers and Support Reps rely on daily - AI drafting tools, autonomous reply systems, workflow automation, reporting dashboards, and anything else that removes friction from the support operation. • Own projects end to end. You're the engineer who takes "this part of the workflow is painful" to "this part of the workflow doesn't exist anymore." No PM intermediary, no thrown-over-the-wall requirements. You work closely with the Support team to understand what to build, then you build it. • Ship customer-facing tools when they take work off the queue. You'll build self-service migration scripts and diagnostic tools customers can run themselves instead of opening a ticket. • Collaborate closely with Support. Reps and Engineers are your primary users and your best source of requirements. You're embedded enough that you see what's actually broken before anyone files a ticket. • Improve the systems underneath the work. Better abstractions, more reliable integrations across Close, Stripe, Twilio, and the rest of the stack. What you build today becomes infrastructure the team builds on tomorrow. • Experiment and ship. The team has real latitude to try new approaches. If there's a better way to do something, you're encouraged to prototype it, measure it, and ship it! Benefits • Compensation: Competitive pay plus an organization-wide goal-based bonus • Paid Time Off: ~5 weeks of PTO to start. Plus a 1-week all-company Winter Holiday Break and paid US holidays. You'll earn 2 extra days for every year you're with Close. • Parental Leave: Paid leave for primary and secondary caregivers • Sabbatical: A 1-month paid sabbatical every 5 years with the team • Healthcare (US residents): Two medical plans with Close covering 99% of your premium, plus Dental, Vision, HSA, FSA, and company-paid Long-Term Disability • 401k (US residents): We match your contributions up to 6%, vested immediately Our Values Build a house you want to live in - Examine long-term thinking and action No BS - Practice transparency and honesty, especially when it's hard Invest in each other - Build successful relationships with your coworkers and customers Discipline equals freedom - Keep your word to yourself and others Strive for greatness - Constantly challenge yourself and others Learn More Listen to our CEO and Founder, Steli Efti, tell the story of Close's journey in the $0-30m Blueprint. Watch our culture video from our 2023 team retreat in Milan. Every year our entire team gathers in person to build connection, foster cross-functional collaboration, and have fun. In 2027, we're headed to Dusseldorf, Germany! Explore our product. Check out a demo! Our Hiring Process We ask a few role-specific questions as part of our application process. These questions are designed to help us learn more about you from the start, so please answer each one thoughtfully. We see this as an opportunity to get to know you beyond your resume. We use AI tools daily at Close and expect candidates to do the same. In evaluating your application, we aim to get a sense for you - the way you think, how you communicate, the work you've done. Applications that read as fully AI-generated will not be considered. Regardless of fit, you can expect to hear back from our team with an update on the status of your candidacy. If you progress to the interview process, you'll receive a full outline of the role-specific steps in your first touchpoint with us. We do our best to make the hiring process clear and human.

Develop and maintain backend distributed systems with AI and telephony integration for real-time communications. | Senior engineer experienced in backend distributed systems, real-time communication, AI integration, and telephony technologies. | About Us Since 2013, we've been building a CRM that gets out of your way and helps your team sell more, faster. Now we're building AI into every part of it, so Close does the busywork and your team does the selling. No manual data entry, no 10-click workflows. Just communication-first, AI-powered sales software designed to help you succeed and scale. We're bootstrapped and profitable which means we answer to our customers and play by our rules. We're proud of our 120-person, 100% remote team, focused on building Close so that no small, scaling business fails because it can't figure out sales. Our Stack Our backend tech stack consists primarily of Python Flask web apps with our TaskTiger scheduler handling many of the backend asynchronous task processing chores. Our data stores include MongoDB, PostgreSQL, Elasticsearch, and Redis. The underlying infrastructure runs on AWS using a combination of managed services like EKS, MSK, RDS and ElastiCache and non-managed services running on EC2 instances. We have CI/CD pipelines that build Docker images, run automated tests and deploy to Kubernetes clusters. We also use these images in our local development environment allowing coding locally against all of our services. We have a well-documented public API that is consumed by our front-end JavaScript app as well as numerous integrations. Our infrastructure is heavily automated using Terraform, Ansible and other AWS tools. We love open sourcing our code and ideas on our GitHub and on The Making of Close, our behind-the-scenes Product & Engineering blog. Check out our open source projects like SocketShark, TaskTiger, LimitLion and ciso8601. AI is both how we build and what we ship, and that's reshaped what engineering looks like. This is a transformation we're embracing and find deeply exciting. About the Role Close moves 7 million minutes of call recordings, millions of sales emails, and a steady volume of SMS through our pipes every month. The Communications team owns that entire surface - and the job got trickier in the last year, because real-time calling is now a real-time AI problem. When a customer tells our AI Agent Chloe to make a call, everything that happens from that moment on - the live call, the conversation itself - belongs to this team. We're looking for someone energized by both sides of the role: the distributed-systems challenges and the AI challenges. One thing to know up front: we do move people between teams as the work shifts. Most engineers here end up on more than one team over their time at Close - this team is where you'll start, but over time you'll likely have the opportunity to work on many different projects. This role is open at multiple levels - Software Engineer, Senior, and Staff. You don't need to pick one when you apply: we'll calibrate together during the process. You Are • A seasoned engineer. Python is our backbone, but perhaps you've worked across Go, Rust, or TypeScript. You pick the right tool for the workload rather than retreating to what you know. • Deeply experienced with email and calendar platforms. IMAP, sync protocols, calendar APIs, and the thousand edge cases of oddly configured enterprise mail servers. This is the experience that makes someone successful on this team fastest. • Fluent in real-time and async distributed systems. WebRTC, WebSockets, queues, streaming. You've debugged a production incident where latency budgets didn't hold. • Opinionated about AI in real-time workflows. You've built or used live transcription, voice agents, or in-the-loop AI features. You have a view on what's ready for production versus what's still a demo. • At home in the gnarly bits. Telephony providers, codecs, retries, eventual consistency. You're drawn to the systems where edge cases actually matter. Deep Twilio or similar telephony experience is a big plus (not a requirement - but a game changer off the bat). • Working with AI in your day-to-day. You use AI tools in your own workflow to ship faster, write tighter code, and reason about unfamiliar parts of the codebase. • A builder first. You'd rather get a sloppy v1 in front of fifty customers than spend three weeks on abstractions. You ship. You Will • Overhaul how Close syncs email and calendars. Our sync engine has run for a decade; we're making a serious, ground-up investment in its performance and reliability. Millions of sales emails and calendar events, and when it breaks, customers feel it within ten minutes. You'd be in the middle of one of the biggest infrastructure rebuilds at Close. • Take voice agents further into the call. We own the live conversation layer for Chloe's calls, and there's a lot of work ahead expanding our voice agent capabilities and infrastructure - including custom models tuned for conversational edge cases like voicemail and automated phone-tree detection (turns out "wait for the beep" is a hard AI problem). • Solve inbound. So far Chloe makes calls; next she answers them. An inbound conversation can go anywhere - which raises real questions about specialized agents, a receptionist layer, and seamless call routing between them. Largely unexplored territory. • Build native scheduling. Core calendar scheduling capabilities inside Close, plus more powerful scheduling for our agents. Various projects landing over the next 6-12 months. • Design human orchestration of an agentic workforce. Agents create work for humans too - things to review, approve, respond to. How do we surface what's happening inside the CRM so each person engages with what actually needs them? A genuinely open product-engineering problem. • Push connect rates and answer rates. Phone number pooling, local presence, branded calling, reputation monitoring. Real revenue impact, real telephony plumbing. • Move our streaming and event substrate forward. Kafka, Redis, pub/sub. The plumbing the rest of the product runs on. Tech you'll touch: Python, Twilio, WebRTC, WebSockets, AssemblyAI, ElevenLabs, Kafka, Redis, PostgreSQL, MongoDB. Benefits • Compensation: Competitive pay plus an organization-wide goal-based bonus • Paid Time Off: ~5 weeks of PTO to start. Plus a 1-week all-company Winter Holiday Break and paid US holidays. You'll earn 2 extra days for every year you're with Close. • 80% Work Option: Work with your manager to choose between a standard 5-day week or a 4-day week at 80% pay • Parental Leave: Paid leave for primary and secondary caregivers • Sabbatical: A 1-month paid sabbatical every 5 years with the team • Healthcare (US residents): Two medical plans with Close covering 99% of your premium, plus Dental, Vision, HSA, FSA, and company-paid Long-Term Disability • 401k (US residents): We match your contributions up to 6%, vested immediately Our Values Build a house you want to live in - Examine long-term thinking and action No BS - Practice transparency and honesty, especially when it's hard Invest in each other - Build successful relationships with your coworkers and customers Discipline equals freedom - Keep your word to yourself and others Strive for greatness - Constantly challenge yourself and others Learn More Listen to our CEO and Founder, Steli Efti, tell the story of Close's journey in the $0-30m Blueprint. Watch our culture video from our 2023 team retreat in Milan. Every year our entire team gathers in person to build connection, foster cross-functional collaboration, and have fun. In 2027, we're headed to Dusseldorf, Germany! Explore our product. Check out a demo! Our Hiring Process We ask a few role-specific questions as part of our application process. These questions are designed to help us learn more about you from the start, so please answer each one thoughtfully. We see this as an opportunity to get to know you beyond your resume. We use AI tools daily at Close and expect candidates to do the same. In evaluating your application, we aim to get a sense for you - the way you think, how you communicate, the work you've done. Applications that read as fully AI-generated will not be considered. Regardless of fit, you can expect to hear back from our team with an update on the status of your candidacy. If you progress to the interview process, you'll receive a full outline of the role-specific steps in your first touchpoint with us. We do our best to make the hiring process clear and human.

Design, develop, and maintain backend systems and APIs with a focus on distributed systems and AI integration. | Senior-level experience in backend development, distributed systems, asynchronous processing, and AI-related workflows, preferably with Python and telephony systems. | About Us Since 2013, we've been building a CRM that gets out of your way and helps your team sell more, faster. Now we're building AI into every part of it, so Close does the busywork and your team does the selling. No manual data entry, no 10-click workflows. Just communication-first, AI-powered sales software designed to help you succeed and scale. We're bootstrapped and profitable which means we answer to our customers and play by our rules. We're proud of our 120-person, 100% remote team, focused on building Close so that no small, scaling business fails because it can't figure out sales. Our Stack Our backend tech stack consists primarily of Python Flask web apps with our TaskTiger scheduler handling many of the backend asynchronous task processing chores. Our data stores include MongoDB, PostgreSQL, Elasticsearch, and Redis. The underlying infrastructure runs on AWS using a combination of managed services like EKS, MSK, RDS and ElastiCache and non-managed services running on EC2 instances. We have CI/CD pipelines that build Docker images, run automated tests and deploy to Kubernetes clusters. We also use these images in our local development environment allowing coding locally against all of our services. We have a well-documented public API that is consumed by our front-end JavaScript app as well as numerous integrations. Our infrastructure is heavily automated using Terraform, Ansible and other AWS tools. We love open sourcing our code and ideas on our GitHub and on The Making of Close, our behind-the-scenes Product & Engineering blog. Check out our open source projects like SocketShark, TaskTiger, LimitLion and ciso8601. AI is both how we build and what we ship, and that's reshaped what engineering looks like. This is a transformation we're embracing and find deeply exciting. About the Role Close moves 7 million minutes of call recordings, millions of sales emails, and a steady volume of SMS through our pipes every month. The Communications team owns that entire surface - and the job got trickier in the last year, because real-time calling is now a real-time AI problem. When a customer tells our AI Agent Chloe to make a call, everything that happens from that moment on - the live call, the conversation itself - belongs to this team. We're looking for someone energized by both sides of the role: the distributed-systems challenges and the AI challenges. One thing to know up front: we do move people between teams as the work shifts. Most engineers here end up on more than one team over their time at Close - this team is where you'll start, but over time you'll likely have the opportunity to work on many different projects. This role is open at multiple levels - Software Engineer, Senior, and Staff. You don't need to pick one when you apply: we'll calibrate together during the process. You Are • A seasoned engineer. Python is our backbone, but perhaps you've worked across Go, Rust, or TypeScript. You pick the right tool for the workload rather than retreating to what you know. • Deeply experienced with email and calendar platforms. IMAP, sync protocols, calendar APIs, and the thousand edge cases of oddly configured enterprise mail servers. This is the experience that makes someone successful on this team fastest. • Fluent in real-time and async distributed systems. WebRTC, WebSockets, queues, streaming. You've debugged a production incident where latency budgets didn't hold. • Opinionated about AI in real-time workflows. You've built or used live transcription, voice agents, or in-the-loop AI features. You have a view on what's ready for production versus what's still a demo. • At home in the gnarly bits. Telephony providers, codecs, retries, eventual consistency. You're drawn to the systems where edge cases actually matter. Deep Twilio or similar telephony experience is a big plus (not a requirement - but a game changer off the bat). • Working with AI in your day-to-day. You use AI tools in your own workflow to ship faster, write tighter code, and reason about unfamiliar parts of the codebase. • A builder first. You'd rather get a sloppy v1 in front of fifty customers than spend three weeks on abstractions. You ship. You Will • Overhaul how Close syncs email and calendars. Our sync engine has run for a decade; we're making a serious, ground-up investment in its performance and reliability. Millions of sales emails and calendar events, and when it breaks, customers feel it within ten minutes. You'd be in the middle of one of the biggest infrastructure rebuilds at Close. • Take voice agents further into the call. We own the live conversation layer for Chloe's calls, and there's a lot of work ahead expanding our voice agent capabilities and infrastructure - including custom models tuned for conversational edge cases like voicemail and automated phone-tree detection (turns out "wait for the beep" is a hard AI problem). • Solve inbound. So far Chloe makes calls; next she answers them. An inbound conversation can go anywhere - which raises real questions about specialized agents, a receptionist layer, and seamless call routing between them. Largely unexplored territory. • Build native scheduling. Core calendar scheduling capabilities inside Close, plus more powerful scheduling for our agents. Various projects landing over the next 6-12 months. • Design human orchestration of an agentic workforce. Agents create work for humans too - things to review, approve, respond to. How do we surface what's happening inside the CRM so each person engages with what actually needs them? A genuinely open product-engineering problem. • Push connect rates and answer rates. Phone number pooling, local presence, branded calling, reputation monitoring. Real revenue impact, real telephony plumbing. • Move our streaming and event substrate forward. Kafka, Redis, pub/sub. The plumbing the rest of the product runs on. Tech you'll touch: Python, Twilio, WebRTC, WebSockets, AssemblyAI, ElevenLabs, Kafka, Redis, PostgreSQL, MongoDB. Benefits • Compensation: Competitive pay plus an organization-wide goal-based bonus • Paid Time Off: ~5 weeks of PTO to start. Plus a 1-week all-company Winter Holiday Break and paid US holidays. You'll earn 2 extra days for every year you're with Close. • 80% Work Option: Work with your manager to choose between a standard 5-day week or a 4-day week at 80% pay • Parental Leave: Paid leave for primary and secondary caregivers • Sabbatical: A 1-month paid sabbatical every 5 years with the team • Healthcare (US residents): Two medical plans with Close covering 99% of your premium, plus Dental, Vision, HSA, FSA, and company-paid Long-Term Disability • 401k (US residents): We match your contributions up to 6%, vested immediately Our Values Build a house you want to live in - Examine long-term thinking and action No BS - Practice transparency and honesty, especially when it's hard Invest in each other - Build successful relationships with your coworkers and customers Discipline equals freedom - Keep your word to yourself and others Strive for greatness - Constantly challenge yourself and others Learn More Listen to our CEO and Founder, Steli Efti, tell the story of Close's journey in the $0-30m Blueprint. Watch our culture video from our 2023 team retreat in Milan. Every year our entire team gathers in person to build connection, foster cross-functional collaboration, and have fun. In 2027, we're headed to Dusseldorf, Germany! Explore our product. Check out a demo! Our Hiring Process We ask a few role-specific questions as part of our application process. These questions are designed to help us learn more about you from the start, so please answer each one thoughtfully. We see this as an opportunity to get to know you beyond your resume. We use AI tools daily at Close and expect candidates to do the same. In evaluating your application, we aim to get a sense for you - the way you think, how you communicate, the work you've done. Applications that read as fully AI-generated will not be considered. Regardless of fit, you can expect to hear back from our team with an update on the status of your candidacy. If you progress to the interview process, you'll receive a full outline of the role-specific steps in your first touchpoint with us. We do our best to make the hiring process clear and human.

Design and improve backend systems handling real-time communications and AI-powered workflows. | Experienced senior engineer with strong Python skills, distributed systems knowledge, and familiarity with asynchronous processing and AI integration. | About Us Since 2013, we've been building a CRM that gets out of your way and helps your team sell more, faster. Now we're building AI into every part of it, so Close does the busywork and your team does the selling. No manual data entry, no 10-click workflows. Just communication-first, AI-powered sales software designed to help you succeed and scale. We're bootstrapped and profitable which means we answer to our customers and play by our rules. We're proud of our 120-person, 100% remote team, focused on building Close so that no small, scaling business fails because it can't figure out sales. Our Stack Our backend tech stack consists primarily of Python Flask web apps with our TaskTiger scheduler handling many of the backend asynchronous task processing chores. Our data stores include MongoDB, PostgreSQL, Elasticsearch, and Redis. The underlying infrastructure runs on AWS using a combination of managed services like EKS, MSK, RDS and ElastiCache and non-managed services running on EC2 instances. We have CI/CD pipelines that build Docker images, run automated tests and deploy to Kubernetes clusters. We also use these images in our local development environment allowing coding locally against all of our services. We have a well-documented public API that is consumed by our front-end JavaScript app as well as numerous integrations. Our infrastructure is heavily automated using Terraform, Ansible and other AWS tools. We love open sourcing our code and ideas on our GitHub and on The Making of Close, our behind-the-scenes Product & Engineering blog. Check out our open source projects like SocketShark, TaskTiger, LimitLion and ciso8601. AI is both how we build and what we ship, and that's reshaped what engineering looks like. This is a transformation we're embracing and find deeply exciting. About the Role Close moves 7 million minutes of call recordings, millions of sales emails, and a steady volume of SMS through our pipes every month. The Communications team owns that entire surface - and the job got trickier in the last year, because real-time calling is now a real-time AI problem. When a customer tells our AI Agent Chloe to make a call, everything that happens from that moment on - the live call, the conversation itself - belongs to this team. We're looking for someone energized by both sides of the role: the distributed-systems challenges and the AI challenges. One thing to know up front: we do move people between teams as the work shifts. Most engineers here end up on more than one team over their time at Close - this team is where you'll start, but over time you'll likely have the opportunity to work on many different projects. This role is open at multiple levels - Software Engineer, Senior, and Staff. You don't need to pick one when you apply: we'll calibrate together during the process. You Are • A seasoned engineer. Python is our backbone, but perhaps you've worked across Go, Rust, or TypeScript. You pick the right tool for the workload rather than retreating to what you know. • Deeply experienced with email and calendar platforms. IMAP, sync protocols, calendar APIs, and the thousand edge cases of oddly configured enterprise mail servers. This is the experience that makes someone successful on this team fastest. • Fluent in real-time and async distributed systems. WebRTC, WebSockets, queues, streaming. You've debugged a production incident where latency budgets didn't hold. • Opinionated about AI in real-time workflows. You've built or used live transcription, voice agents, or in-the-loop AI features. You have a view on what's ready for production versus what's still a demo. • At home in the gnarly bits. Telephony providers, codecs, retries, eventual consistency. You're drawn to the systems where edge cases actually matter. Deep Twilio or similar telephony experience is a big plus (not a requirement - but a game changer off the bat). • Working with AI in your day-to-day. You use AI tools in your own workflow to ship faster, write tighter code, and reason about unfamiliar parts of the codebase. • A builder first. You'd rather get a sloppy v1 in front of fifty customers than spend three weeks on abstractions. You ship. You Will • Overhaul how Close syncs email and calendars. Our sync engine has run for a decade; we're making a serious, ground-up investment in its performance and reliability. Millions of sales emails and calendar events, and when it breaks, customers feel it within ten minutes. You'd be in the middle of one of the biggest infrastructure rebuilds at Close. • Take voice agents further into the call. We own the live conversation layer for Chloe's calls, and there's a lot of work ahead expanding our voice agent capabilities and infrastructure - including custom models tuned for conversational edge cases like voicemail and automated phone-tree detection (turns out "wait for the beep" is a hard AI problem). • Solve inbound. So far Chloe makes calls; next she answers them. An inbound conversation can go anywhere - which raises real questions about specialized agents, a receptionist layer, and seamless call routing between them. Largely unexplored territory. • Build native scheduling. Core calendar scheduling capabilities inside Close, plus more powerful scheduling for our agents. Various projects landing over the next 6-12 months. • Design human orchestration of an agentic workforce. Agents create work for humans too - things to review, approve, respond to. How do we surface what's happening inside the CRM so each person engages with what actually needs them? A genuinely open product-engineering problem. • Push connect rates and answer rates. Phone number pooling, local presence, branded calling, reputation monitoring. Real revenue impact, real telephony plumbing. • Move our streaming and event substrate forward. Kafka, Redis, pub/sub. The plumbing the rest of the product runs on. Tech you'll touch: Python, Twilio, WebRTC, WebSockets, AssemblyAI, ElevenLabs, Kafka, Redis, PostgreSQL, MongoDB. Benefits • Compensation: Competitive pay plus an organization-wide goal-based bonus • Paid Time Off: ~5 weeks of PTO to start. Plus a 1-week all-company Winter Holiday Break and paid US holidays. You'll earn 2 extra days for every year you're with Close. • 80% Work Option: Work with your manager to choose between a standard 5-day week or a 4-day week at 80% pay • Parental Leave: Paid leave for primary and secondary caregivers • Sabbatical: A 1-month paid sabbatical every 5 years with the team • Healthcare (US residents): Two medical plans with Close covering 99% of your premium, plus Dental, Vision, HSA, FSA, and company-paid Long-Term Disability • 401k (US residents): We match your contributions up to 6%, vested immediately Our Values Build a house you want to live in - Examine long-term thinking and action No BS - Practice transparency and honesty, especially when it's hard Invest in each other - Build successful relationships with your coworkers and customers Discipline equals freedom - Keep your word to yourself and others Strive for greatness - Constantly challenge yourself and others Learn More Listen to our CEO and Founder, Steli Efti, tell the story of Close's journey in the $0-30m Blueprint. Watch our culture video from our 2023 team retreat in Milan. Every year our entire team gathers in person to build connection, foster cross-functional collaboration, and have fun. In 2027, we're headed to Dusseldorf, Germany! Explore our product. Check out a demo! Our Hiring Process We ask a few role-specific questions as part of our application process. These questions are designed to help us learn more about you from the start, so please answer each one thoughtfully. We see this as an opportunity to get to know you beyond your resume. We use AI tools daily at Close and expect candidates to do the same. In evaluating your application, we aim to get a sense for you - the way you think, how you communicate, the work you've done. Applications that read as fully AI-generated will not be considered. Regardless of fit, you can expect to hear back from our team with an update on the status of your candidacy. If you progress to the interview process, you'll receive a full outline of the role-specific steps in your first touchpoint with us. We do our best to make the hiring process clear and human.