Close

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

Close$120K — $160K *
US-AnywhereRemote in United States
Enterprise Technology
Less than 5 years of experience
Job Overview by Ladders

Qualifications

  • 5-7 years of software engineering experience
  • Proficiency in Python and experience with Go, Rust, or TypeScript
  • Experience shipping AI features with a focus on usability
  • Familiarity with AI tools for productivity
  • Strong background in debugging and real-time system monitoring
  • Ability to comprehend and analyze academic papers in AI and machine learning
  • Comfortable working with non-deterministic systems

Responsibilities

  • Ship code execution for AI assistants, including generating charts and tables
  • Build evaluation and observability layers for agent performance
  • Develop user interfaces driven by the backend and LLMs
  • Transform custom agent prototypes into general availability products
  • Integrate deterministic workflows with AI-driven components
  • Manage edge cases for operational reliability of agents
  • Select appropriate models for varied tasks and optimize usage

Benefits

  • Opportunity to work across multiple teams and projects over time
  • Access to cutting-edge AI technologies and tools
  • A culture focused on rapid iteration and deployment
  • Exposure to a diverse set of engineering challenges
  • Collaboration with a knowledgeable team in a high-stakes environment
Full Job Description
We shipped our first agent, 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 everyone else relied on, or carried a pager for something with real customer impact.
  • Close to the research. You read papers, or you've spent serious time in retrieval, RAG, RLHF, or fine-tuning. Not a researcher, but you can read one and tell us whether the result matters for our problem.
  • Comfortable with non-determinism. Much of your output is probabilistic. Conventional patterns don't hold. You find this fun.


You will
  • Ship code execution for the assistant. The assistant decides when writing code beats answering non-deterministically - today that's generating charts and tables in Python on the fly; next it's reusable user-defined tools and calling external APIs to pull in whatever data the task needs.
  • Build the eval and observability layer that tells us when an agent is getting better. Unit tests don't cut it for non-deterministic output. We run evals and tracing (LangFuse and our own tooling) as the bar for shipping: if we can't measure it, we don't ship it.
  • Push generated UI forward. The backend increasingly decides what the user sees - the LLM picks the right presentation (table, chart, widget) and renders it in the assistant, with a full-screen experience and stored, referenceable artifacts on the roadmap. Effectively: customers generate the reports we used to hand-build, one custom report at a time.
  • Take Custom Agents from prototype to GA. Event-driven agents that act on what's happening inside the CRM in real time - an email lands, an agent drafts the reply from knowledge sources and context, the user approves. This is where we differentiate from the general-purpose assistants: we see the events, we have the context.
  • Make deterministic and non-deterministic systems work together. Sales processes need steps that happen every single time; LLMs are bad at that. You'll help fuse our Workflows engine with agentic steps so customers get reliability where it matters and intelligence where it helps.
  • Handle the edges that make agents trustworthy. What happens to a fleet of running agents when a customer's AI credits run out? Pause semantics, recovery, and making sure nothing places a hundred calls that were supposed to happen last week.
  • Pick the right model for the job. We use many providers, test new models constantly, and are moving toward cost-aware routing - simple summarization jobs shouldn't run on frontier-priced models. You'll call when something is production-ready and when it's still a demo.


Tech you'll touch: Python, Temporal, LangFuse, Pydantic, ElevenLabs, MCP, PostgreSQL, MongoDB - plus whichever LLM ships next.

About Close

Close is a sales CRM for startups and SMBs. The platform helps businesses manage their sales process by providing a suite of tools for lead management, email marketing, and reporting. Close was founded in 2013 by Steli Efti, Nick Persico, and Anthony Nemitz.
Learn more about Close
Size
100 employees
Industry

Similar Jobs

More Jobs at Close

More Enterprise Technology Jobs

Find similar Senior Backend Engineer - Agents (USA Only - 100% Remote) jobs: