Ruby Engineer

Process billions of rows, optimize massive datasets, and tackle complex database challenges. Join Koinly to push Ruby and SQL performance to the limit in a high-scale, async-first environment., * Main responsibilities: Design, optimize, and scale Ruby backend services handling billions of records, ensuring performance, reliability, and clean code at massive scale., We've hit product-market fit in a high-scale, complex financial domain. Now we need to keep pushing performance and reliability while shipping new features. That means solving hard problems in:

• Data architecture: Making billions of rows and massive CSVs play nicely with high-throughput APIs.
• Performance optimization: Query tuning, caching strategies, background job orchestration.
• System design: Scaling Ruby microservices that process terabytes of data without falling over.

• 6+ years of professional Ruby experience.
• Strong SQL skills, including performance tuning and complex queries.
• Strong problem-solving and debugging skills.
• Experience designing and scaling backend systems (microservices, APIs, background jobs).
• Eagerness to work with a high-standard engineering team, CI/CD, and testing.
• A track record of taking full ownership of complex features or systems.
• Comfort with feedback loops and a high-ownership mindset., * Experience with high-volume CSV/data ingestion pipelines.
• Familiarity with performance profiling tools in Ruby.
• Background in DeFi, blockchain, or fintech.
• Side projects that show your love for technical puzzles.

• Work with huge datasets (billions of transactions) and make them fast, reliable, and cost-efficient.
• Debug gnarly production issues that live at the intersection of code, data, and infrastructure.
• Write clean, tested, maintainable Ruby that holds up under scale.
• Champion performance, clarity, and simplicity in code and system design.
• Occasionally take part in on-call rotation (we have very few prod issues, high coverage, and careful releases are the norm here).
• Stay up-to-date with emerging technologies and best practices in Ruby development.

At Koinly, we're looking for a Senior Ruby Developer to help design, build, and maintain scalable backend systems that power crypto tax reporting for over 1.5 million crypto investors. You'll write clean, efficient, and high-performance code. Not to just ship new features, but to continuously optimize speed, reliability, and user experience across our Ruby (and Ruby on Rails)-powered architecture. We need an engineer who thinks in data pipelines, indexes, and execution plans, not just models and controllers. Someone who gets irrationally motivated by shaving milliseconds off a query, or turning an hour-long CSV import into minutes. We're a fully remote-first, async-first startup with product-market fit in a niche (and booming) domain: crypto taxes. If you value autonomy, technical excellence, and clear communication over meetings and process complexity, Koinly is the place for you.