Fullstack Engineer

Responsibilities

• Own end-to-end product work across the agent experience including flows, integrations, and UI/UX
• Develop flows for creation, editing, run criteria, execution reliability, and observability
• Add new integrations and deepen existing ones
• Work on novel ways of building human-agent interactions
• Ship features across the full stack with a tight feedback loop from real users
• Improve performance, reliability, and cost across agent runs and flow execution
• Build instrumentation, analytics, and developer tooling to speed up iteration
• Maintain high standards for code quality, tests, observability, and documentation

Requirements

• 4+ years of experience building and shipping user-facing products end to end
• Frontend expertise in React/Next.js and TypeScript
• Backend expertise in Python FastAPI, background workers/queues, webhooks, and Postgres
• Strong testing and observability habits including unit/integration tests and structured logs
• Bias to ship by scoping thin slices and delivering quickly

Preferred Qualifications

• Experience with event-driven architectures like Inngest or Temporal
• Knowledge of WebSockets and real-time UIs
• LLM/agent experience including tool-use patterns, prompt hygiene, and evaluation
• Familiarity with infrastructure such as Render, Modal, Supabase, or Redis Cloud
• Experience with CI/CD and feature flags

About the Company

Cofounder is an autonomous agent platform that connects to your tools to run workflows end to end. We’re building the operating system for one-person, billion-dollar companies.