AI Applications Engineer

Build and run the AI companions COROS deploys inside other companies. A full stack lead role: you own one end to end.

RemoteFull-timeLead role

Who we are

When AI can do the work, the conversation becomes the work. COROS exists to make people extraordinary at the work no machine can do: the conversations that decide a career, a team, a marriage, a life. Our mission is to reintroduce care and communication as the operating system of any thriving community.

We stand on a forty-year tradition on language, moods, and coordination in a new technological form. Small team, senior people, globally distributed. Everyone here works on themselves as seriously as they work on the product.

About this role

The COROS engine now also powers companions we build and run for other companies: their domain, their users, their brand, our engine underneath. This is the lead engineering role on our largest engagement, and it combines the front end and back end roles we hired for last year. You are the person who holds the whole system in their head.

Client background

[Shared as confidential under NDA]

What you’ll do

  • Own a client companion end to end: agents, tools, retrieval, the app, the backend, deployment, and the cost of running it.
  • Build on Claude: streaming tool-use loops, structured outputs, prompt caching, and evaluations that catch a wrong answer before a user sees it.
  • Build stateful agents that remember, schedule work, and act on their own.
  • Ground every answer in cited sources. The model never improvises on law, money, or process.
  • Migrate production data off legacy systems without losing a record.
  • Ship weekly with the client’s product owners, and write down what shipped.

What you’ll work with

  • TypeScript everywhere. Next.js, React, Tailwind, shadcn/ui and Redux Toolkit on the COROS product; Vite and Cloudflare Workers on client companions.
  • Claude and the Anthropic SDK: tool use, structured outputs, streaming, prompt caching.
  • Retrieval and memory: RAG over a curated corpus, vector search, a long-term memory layer.
  • Backends on Google Cloud (Cloud Run, Artifact Registry), Azure (Web Apps, Container Registry) and AWS. Docker, GitHub Actions, containers you can debug.
  • Cloudflare Workers, Durable Objects, D1, R2, Vectorize, Wrangler.
  • Postgres and SQLite, and migrations out of legacy MySQL.
  • Voice with Azure Speech and ElevenLabs. Mobile with Expo and EAS.
  • Stripe, Resend, Cloudinary, multi-provider OAuth.
  • Sentry and Mixpanel on every error path and every interaction. Playwright and Vitest for tests.
  • Claude Code and VS Code, daily. Figma. Git and GitHub, small reviewed pull requests.

What we’re looking for

  • A bachelor’s degree in computer science or a closely related field. Exceptions for extraordinary candidates who can show the work.
  • Three or more years shipping full stack software that real users depended on. You have been on call for something you built.
  • Real backend experience: APIs, relational data, background jobs, containers, deployments. You can stand a service up and keep it running.
  • Strong TypeScript, and the fundamentals under it: HTTP, SQL, concurrency, data structures.
  • Working knowledge of at least one major cloud (Google Cloud, AWS or Azure), and the willingness to learn the others.
  • Real fluency with Claude Code and VS Code. Tell us what you have built with them.
  • Production experience with language models: prompting, context, tool use, retrieval, evaluation, latency, cost.
  • Clear English, written and spoken. You will explain decisions to founders who are not engineers.

Who you are

  • Humble, and genuinely open to learning. This is a lead role, and leading here means being corrected, changing your mind, and doing both without friction.
  • Open to coaching. Everyone at COROS works on themselves as seriously as they work on the product. Here that is the work, not an add-on.
  • Patient, and careful with people. Much of what a user tells a companion, they have told no one else.
  • A good communicator. You ask before building the wrong thing, and say early when something is stuck.
  • Fast without being careless. Nothing about law, money, or safety is ever guessed.

Nice to have

  • Edge runtimes or stateful serverless systems
  • Migrating a legacy application without downtime
  • Multilingual product work
  • Evaluation and safety testing for language-model applications

Sound like you?

Write to [email protected]: why this work matters to you, something you have built, and what you have done with Claude Code.

Apply for AI Applications Engineer →