Staff Software Engineer

Architect the systems that make crypto tax simple and performance effortless

Koinly simplifies crypto taxes for millions of users. Our cryptocurrency tax platform transforms billions of blockchain transactions into accurate financial records through reliable, high-performance engineering.

We're hiring a Staff Software Engineer to join our Engineering team. The mission of this role is to strengthen our Ruby systems by simplifying complexity, improving performance, and shaping the architecture that keeps financial data precise and fast.

Koinly is a remote-first and async by design, with strong product-market fit in a niche (and booming) domain: crypto taxes. If you thrive on deep technical work and value autonomy, clarity, and craft, you'll fit right in.

Apply below to help build the backbone of large-scale financial systems.

Key details in sum

Location: Remote - preference for Europe-based candidates.

Salary: USD $100K-115k / year.

Contract type: Full-time (B2B contractor).

Perks:

• 32 days of PTO.
• Async culture.
• Flexible work-schedule.
• A culture of high autonomy and ownership.

Experience level: 7+ years.

️Start date: ASAP.

Team size: 10 person engineering team.

Main responsibility: Engineer and optimize high-performance Ruby systems that handle billions of financial transactions, solving deep scaling, data, and code-quality challenges.

Why this role exists

As Koinly scales, we need our backend systems to stay fast, reliable, and accurate. This Staff Engineer will provide hands-on technical excellence to optimize reliability and simplify complex pipelines as we scale to billions of transactions.

As a Staff Engineer at Koinly, you'll stay deeply hands-on while anchoring complex projects, guiding technical direction, and sharing knowledge that raises the bar for the whole team. We value engineers who think independently, stay curious, and communicate with clarity. Collaboration here means solving hard problems together, giving direct feedback, and continuously improving how we build at scale.

What you'll do:

• Design and develop scalable backend systems that process billions of financial transactions.
• Provide technical direction across projects and collaborate with product and engineering leads to define priorities and architecture.
• Own project delivery: from design and implementation to performance and reliability in production.
• Refactor and modernize core Ruby systems to improve maintainability, readability, and speed.
• Mentor other engineers through technical reviews, design discussions, and clear documentation.

What you bring:

• 7+ years of backend experience with Ruby on Rails at scale, with at least 2 years as a senior engineer, influencing cross-team initiatives.
• Proven record improving system performance and code quality.
• Strong understanding of data flows and software design principles.
• Experience working cross-functionally in async, remote environments.
• Clear communication and ownership mindset.

Bonus:

• Experience tuning Postgres in production.
• Built or optimized data ingestion or reconciliation pipelines.
• Open-source contributions to Ruby, Rails, or performance tooling.
• Background in fintech, taxtech, open banking, or blockchain systems.

Koinly's engineering culture

️ Craftsmanship matters: we value deep thinking, well-structured systems, and clean code.

Async-first collaboration: clarity and autonomy come through written communication.

Impact through ownership: engineers drive projects end to end.

Remote: we trust people to work flexibly and deliver excellence from anywhere.

Why join Koinly

Built for builders: A profitable, bootstrapped startup in a hyper-growth industry.

Pure Ruby backend: No language sprawl or over-engineering.

Autonomy-first: Async communication, deep work, minimal meetings.

Massive scale: Billions of trades and 950+ integrations.

Small team, big impact: Millions of users, 37 people company-wide.

No corporate theatre: Zero bureaucracy, high trust, high ownership.

Flexible by default: Fully remote, async, and results-oriented.

Crypto-adjacent without the hype: We're a painkiller, not a multivitamin.

Join Koinly and design systemsof crypto tax at massive scale. Apply today!

Due to the nature of our business and external requirements, we perform background checks on all potential team members, passing which is a prerequisite to join Koinly.