Senior Software Engineer - Backend (USA Only - 100% Remote)

About Us

Close is building the CRM for the next generation of small scaling businesses. We are bootstrapped, profitable, and fully remote, with about 120 people. We run on Python; Go or Rust experience is welcome too. We move 7 million minutes of call recordings and millions of sales emails a month, operate at billions of MongoDB documents and petabytes of network traffic, and we run AI in production for 11,000 paying customers.

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.

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.
  

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 be also be evaluating skillset fit and the need of the business at any time.

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.
  

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 ElasticCache 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.

Benefits

• Competitive compensation including an organization-wide goal-based bonus

• Paid Time Off: 5 Weeks PTO upon joining + Winter Holiday Break. Each year with the company, you’ll receive 2 additional PTO days

• 80% Work Option: Work with your manager to choose between working 5 day weeks (standard full-time) or 4 day weeks @ 80% pay

• Paid Parental Leave for primary and secondary caregivers

• Sabbatical: After 5 years with the team, you’re eligible for a 1 month paid sabbatical 

• Healthcare (US residents): Medical, Dental, Vision with HSA option (US residents), Dependent care FSA (US residents)

• 401k (US residents): We match 6% contributions with immediate vesting

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 2026, we’re headed to Barcelona, Spain!

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 question 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 do too. In evaluating your application, we aim 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 interview process in your first touchpoint with us. We do our best to make the hiring process clear and human.