At Koinly, we’re looking for a Tech Lead (Ruby on Rails) to push our financial data platform to the next level. This role is roughly 80% coding, 20% technical leadership and is ideal for a senior engineer who thrives on solving performance bottlenecks, guiding peers, and shaping architecture without the management overload. 

More about us is included at the end of this page.

🔑 Key details

• Report to: Engineering Manager
• Squad: Core
• Team size: 5 senior engineers (within a 10-person backend group)
• Location: Remote, preference for Europe-based candidates
• Salary: USD $100k–120k / year 
• Type: Full-time (B2B contractor)
• Experience: 7+ years, prior leadership of senior peers
• Start date: ASAP
• Mission: Lead a small senior team while staying hands-on to solve performance bottlenecks and push technical excellence.

🚀 The challenge ahead

Koinly’s backend reconciles billions of crypto transactions across 900+ integrations. Every millisecond and data point must be accurate. As usage surges, the challenge is keeping our systems fast, reliable, and easy to evolve.

You’ll lead the effort to:

• Keep performance high as scale increases.
• Refactor and simplify complex Ruby systems.
• Mentor senior peers and shape the next generation of our backend architecture.

  
  

Clean code and clarity at massive scale, that’s the mission.

🛠️ What you’ll do

Performance and reliability

• Profile, tune, and reduce latency across high-volume ingestion and reconciliation systems.

• Optimize Postgres queries, caching, and background processing.

Architecture and refactoring

• Own and evolve our Ruby + Postgres backend.

• Lead major refactors to improve maintainability and scalability.

• Design data flows and pipelines that reconcile billions of records accurately.

Technical leadership

• Set coding standards, review designs and pull requests, and coach senior engineers through code review.

• Leadership through mentoring, reviews, and technical decision-making (without management overhead).

Collaboration

• Collaborate asynchronously with product, design, and leadership.
• We're light on meetings, heavy on ownership. 
• Collaborate through lightweight RFCs and clear written communication

What success looks like?

You’ll make our systems faster, our codebase simpler, and our engineering culture stronger.

🧠 What you bring

• 7+ years’ experience and deep proficiency in Ruby on Rails.
• Proven results improving performance and reliability in production databases (Postgres preferred).
• Strong async communication and mentoring skills.
• Track record of solving performance issues through thoughtful design and clean code.
• Ability to analyze and simplify complex systems.
• Experience with data pipelines, ETL, or reconciliation systems.

Bonus points:

• You have experience working in an async-first, distributed team.
  
• You've tuned Postgres in production.
• Debugged concurrency issues (deadlocks, race conditions).
• Worked in fintech, taxtech, open banking, or other regulated data domains.
• Familiarity with blockchain or DeFi data structures. 
• Understanding of observability practices (metrics, tracing, SLOs).

❎ Don’t meet every checkbox? That’s fine. We care about skill, drive, and how you think.

⚙️ Koinly engineering culture

• Engineering-led values: 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, no