Founding Backend Engineer

Your mission

ControlResell runs on Vinted, eBay and Shopify today. Within twelve months we have to ship eight new marketplace connectors (Grailed, Vestiaire, Leboncoin, Depop, Etsy, Poshmark, Facebook Marketplace, Mercari) and keep the whole thing running in production without breaking.

You join Nathan, our CTO, to carry the Kotlin/Ktor backend through this transition. You own the marketplace connectors and build the observability that catches problems before users do.

What you'll have done in 12 months

• Ten marketplaces live in production. Time-to-ship of a new connector under two weeks by M+12.
• Unit and integration test coverage above 80% on critical flows. E2E tests on the critical flows.
• Structured logs across all services, alerting under ten minutes on regressions, real-time monitoring dashboards.
• Sole owner of backend bugs. Critical bug fixed within six hours, minor within twenty-four hours on working days. Post-mortem documented for every major incident to prevent regressions.
• Continuous performance optimization. Efficient caching on critical flows. Infrastructure cost under control.

Your first 90 days

Month 1. You ship your first connector pair-programming with Nathan. You take ownership of the stack: Ktor, Coroutines, Kourier, Redis, MySQL, RabbitMQ and K8s. You debug a first scraping incident in prod.

Month 3. You own two marketplaces autonomously. You've set up structured logs and a monitoring dashboard for your connectors. You've already fixed critical incidents in prod.

Month 6. You own the entire backend stack autonomously. You drive architecture choices, monitoring, incident management.

Who we're looking for

• You've shipped a backend in production with real load: concurrent users, requests per second, nighttime incidents. You can tell us about a slow query you fixed and the EXPLAIN that guided you.
• You're fluent in Kotlin (or coming from Java with the appetite to learn Kotlin in two to four weeks). Coroutines, structured concurrency, Result types, you know what we're talking about.
• You can handle production incidents without panicking: you can analyze logs, debug cold, write a constructive post-mortem and prevent regressions.
• You're comfortable with relational databases (MySQL or equivalent), message queue systems (RabbitMQ or equivalent) and caching systems (Redis or equivalent).
• You're proactive on maintenance and continuous improvement: you don't just fix bugs, you look for root causes.
• You use Claude Code or Cursor heavily in your workflow but you review every output.

Nice to have. You've worked on connectors (scraping and external integration) in production before. You're active in the open source community.

This role isn't for you if

• You refuse to learn Kotlin (we code in Kotlin, not Java).
• You write clean code but don't think about the product or the end user.
• You refuse to touch any language other than Kotlin or Java. (We have Python, JS, TypeScript, etc.)
• You don't want to be woken up at 3am occasionally for a critical incident. It's rare but it happens.

Perks

• Salary €90K–€110K gross/year
• BSPCE 0.5% to 1.5%, 4-year vesting, 1-year cliff
• ControlResell house 30 min from Paris by RER
• Chef, lunch and dinner on days you're in
• Unlimited vacation
• MacBook Pro M-series and €2,000 hardware budget
• Claude Code Max subscription and premium tools for your stack
• 3 months in the US at Silicon Valley within 18 months
• Conference budget
• 20% of your time on open source, side projects, R&D, technical articles, etc. — your choice, aligned with our mission.

Process

1. Call 1 with Lyes (30 min). Vision, mission, energy.
2. Call 2 with Nathan (60-65 min). Live technical test, three exercises: a mini Ktor service with a Redis quota check, a code review of one of your repos, an architecture discussion on the Vestiaire Collective integration.
3. Call 3 with Lyes and Nathan (45 min). Debrief, package, questions.
4. Dinner at the CR house.
5. Formal offer within 24h.