Senior Backend Engineer – Agents (USA Only - 100% Remote)

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 https://stackshare.io/close-crm/close consists primarily of Python Flask web apps with our TaskTiger https://github.com/closeio/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 https://developer.close.com/ 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 https://github.com/closeio and on The Making of Close https://making.close.com/, our behind-the-scenes Product & Engineering blog. Check out our open source projects like SocketShark https://github.com/closeio/socketshark, TaskTiger https://github.com/closeio/tasktiger, LimitLion https://github.com/closeio/limitlion and ciso8601 https://github.com/closeio/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 We shipped our first agent, Chloe https://close.com/chloe, in 2026. The Agents team owns the platform underneath: the agent core, the eval and observability layer, the MCP surface that external agents (Claude, ChatGPT, ElevenLabs, n8n) operate Close through, and the orchestration that ties it together. The team is running three major streams right now: Voice Agents, the LLM-powered chat assistant, and Custom Agents. Most of the engineering problems here didn't exist a year ago. We're figuring them out in code, in production, in front of 11,000 paying customers. 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. - AI-native in production. You've shipped meaningful, impactful agentic features to users. You have opinions on retrieval, evals, tool design, context engineering, and where the current frontier models fall over. - 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. You have a POV on where they help and where they get in the way. - A builder first. You'd rather get a sloppy v1 in front of fifty customers than spend three weeks on abstractions. You ship. - Battle-tested. You've debugged incidents where latency budgets didn't hold, owned a system…