Lead Full-Stack Engineer
Hands-on Lead Full-Stack Engineer at ARIMLABS, an early-stage company building a platform that authors and quality-checks reinforcement-learning tasks for frontier AI labs. You ship features across a FastAPI backend and Next.js frontend using AI coding agents daily, and establish engineering practices from scratch.
- Compensation
- Not disclosed
- Location
- Not listed
- Work setup
- Remote
- Seniority
- Lead
- Employment
- Full time
- Experience
- Not specified
- Category
- Fullstack
- Posted
Skills
Must have
- Track record of shipping production software as a hands-on senior or lead engineer
- Daily use of AI coding agents (Claude Code, Cursor, Codex or similar)
- Strong Python: FastAPI, SQLAlchemy, asyncio
- TypeScript and React (Next.js)
- PostgreSQL
- Builder mentality: creating systems and processes, solving ambiguous problems
- Strong ownership and autonomy, driving work to measurable results without constant supervision
- Pragmatic approach to quality: practices that protect a team without ceremony that slows it down
- Ambition and drive: highly motivated, resourceful, results-oriented, ready to lead a team
Nice to have
- Experience establishing engineering practices in a startup or high-growth company
- Experience combining hands-on development with tech-lead or team-lead responsibilities
- Experience improving a codebase written largely by AI agents
- Experience building agent tooling: project context files, custom review prompts, MCP servers
- Experience with marketplaces, payouts or review workflows where correctness carries money
- Exposure to LLM evaluation, reinforcement learning or AI research tooling
Full description
We're looking for an ambitious, hands-on Lead Full-Stack Developer who builds with AI coding agents every day and knows how to make that fast and reliable.
Our platform builds and quality-checks reinforcement-learning tasks for frontier AI labs: authoring, review, automated QA in cloud sandboxes, and customer acceptance. It's built quickly by a small team working heavily with AI agents. This is an opportunity to own how we build software: ship features, spot what to improve, deliver our roadmap, and establish engineering practices from scratch. You can then grow into leading the engineering team.
What You'll Do
Ship, constantly: Take feature requests from our researchers, reviewers and operators, and deliver them to production within days, across a FastAPI backend and a Next.js frontend.
Vibe code with discipline: Build with AI coding agents as your main tool, and set the standard for doing it well: clear context, tight scope, tests that mean something, and diffs that get read.
Establish engineering best practices from 0 to 1: Introduce code review, linting, testing and CI gates that make the team safer without slowing it down.
Find what to improve: Spot weak points in the code and product, such as tangled modules, missing tests or slow pages, and fix them incrementally while features keep shipping.
Deliver the plan: Turn our existing roadmap into sequenced, shippable work, and push back with evidence when something should change.
Guard correctness where it matters: Make sure the rules behind reviews, acceptance and payouts are enforced in code and covered by tests.
Shape the future team: Review others' work, mentor, share knowledge, and potentially lead the engineering team as it grows.
What We're Looking For
Proven engineering experience: A track record of shipping production software as a hands-on senior or lead engineer.
AI-native workflow: You build with Claude Code, Cursor, Codex or similar every day, and you have opinions on how to keep agent-written code correct.
Full-stack generalist: Strong Python (FastAPI, SQLAlchemy, asyncio), TypeScript and React (Next.js), and PostgreSQL. Comfortable with any part of the stack on any given day.
Builder mentality: You enjoy creating systems and processes, solving ambiguous problems, and taking ideas all the way to production.
Strong ownership and autonomy: You take responsibility for the things nobody else sees, because you see them. You drive them to measurable results without constant supervision.
Pragmatic quality: You know the difference between practices that protect a team and ceremony that slows it down.
Ambition and drive: A highly motivated, resourceful and results-oriented person who wants to grow quickly, stays hands-on, and is ready to lead a team forward.