Full Stack Product Engineer - Applied Algorithms

Description: We’re hiring a senior full-stack engineer to own significant parts of a production multi-tenant SaaS product. The platform combines original algorithms, multi-stage AI pipelines, and integrations with third-party platforms. This is not a role where we teach you how to build software. We want an experienced engineer who already ships production code and uses AI tools (Claude Code, Cursor, Codex, or similar) to move faster. Please read this part carefully: the codebase is complex enough that pointing an AI agent at a task and accepting what it produces does not work. We’ve tried it. You need to understand the system yourself, give the AI the right context, read and verify everything it writes, and catch it when it’s confidently wrong. AI is your accelerator, not your substitute. What you’ll do Build and refine product logic: algorithms, data transformations, and AI pipelines where model output has to be constrained, validated, and combined with deterministic code Trace problems across the frontend, API, database, background workers, and final output Take features from requirement through release, and verify what the customer actually sees Work directly with the founder on how the product should behave Stack JavaScript throughout. Node.js 20 and Express, PostgreSQL with direct SQL and migrations (no ORM), React 19 with Vite and Tailwind. Deployed on Railway with background worker processes and some Cloudflare Workers. Integrates OpenAI and Anthropic APIs. You should have Senior-level experience shipping production web apps across frontend, backend, and database Strong SQL and PostgreSQL skills Real experience putting LLMs into production software, not just prompting in a chat window A daily AI-assisted development workflow you can describe concretely The ability to work independently with clear written communication Engagement Hourly, long-term. 20-40 hours/week. At least 4 hours of overlap with Eastern Time. Process Proposal review Short call about work you’ve done Paid trial on a small, scoped, representative task Ongoing contract To apply Start your proposal with the word “Railway” so we know you read the post. Proposals that don’t will be skipped. Answer the screening questions in your own words. Short and specific beats long and generic.