Senior Backend Engineer (Ruby on Rails)

What you’ll do

• Own backend services end-to-end: design, build, refactor, optimize.
• Push Ruby and SQL performance: query plans, indexing, caching, background jobs.
• Work on high-volume data pipelines (CSV ingestion, cost-efficient processing).
• Debug real production issues across code, data, and infrastructure.
• Champion simplicity, observability, and maintainable code in a high-scale system.

Requirements

• 6+ years professional Ruby experience (Rails at scale a plus).
• Strong SQL skills, including performance tuning and complex queries.
• Proven experience designing and scaling backend systems (APIs, jobs, services).
• Comfortable in async, remote teams; strong written communication.
• High ownership mindset: you like taking a problem from idea to production.

How we work

• Remote-first, async-first, minimal meetings.
• Small engineering team (~10 devs), large-scale impact (millions of users).
• Pure Ruby backend, no language sprawl, high bar for code quality and tests.

Koinly engineering culture

• Engineering-led: Maintainability, test coverage, and reliability come before shipping speed.
• Craftsmanship mindset: We care deeply about clean, readable code that scales gracefully.
• No heroics: Systems are built to be stable, observable, and easy to debug.
• Autonomy & accountability: Small squads, high ownership, minimal bureaucracy.
• Async-first & remote-first: We collaborate primarily through clear writing, not constant meetings.