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- Tasks: Design and optimise scalable Ruby systems for processing billions of financial transactions.
- Company: Join Koinly, a remote-first startup revolutionising crypto tax solutions.
- Benefits: Enjoy 32 days of PTO, flexible schedules, and a culture of autonomy.
- Why this job: Make a real impact in the booming crypto tax industry with cutting-edge technology.
- Qualifications: 7+ years of backend experience with Ruby on Rails and strong problem-solving skills.
- Other info: Collaborate in a small team, drive projects end-to-end, and thrive in a dynamic environment.
The predicted salary is between 72000 - 84000 £ per year.
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 are 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.
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.
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 systems of 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.
Staff Software Engineer in City of London employer: Koinly
Contact Detail:
Koinly Recruiting Team
StudySmarter Expert Advice 🤫
We think this is how you could land Staff Software Engineer in City of London
✨Tip Number 1
Network like a pro! Reach out to your connections in the tech world, especially those in fintech or crypto. A personal recommendation can make all the difference when you're aiming for that Staff Software Engineer role.
✨Tip Number 2
Show off your skills! Create a portfolio showcasing your Ruby projects, especially any that involve performance optimisation or complex data flows. This will give potential employers a taste of what you can bring to the table.
✨Tip Number 3
Prepare for technical interviews by brushing up on system design and performance tuning. Be ready to discuss how you've tackled scaling challenges in the past, as this is key for a role focused on high-performance systems.
✨Tip Number 4
Don’t forget to apply through our website! It’s the best way to ensure your application gets seen by the right people. Plus, it shows you’re genuinely interested in joining Koinly and contributing to our mission.
We think you need these skills to ace Staff Software Engineer in City of London
Some tips for your application 🫡
Tailor Your Application: Make sure to customise your CV and cover letter for the Staff Software Engineer role. Highlight your experience with Ruby on Rails and any relevant projects that showcase your ability to handle complex systems and improve performance.
Showcase Your Technical Skills: Don’t just list your skills; demonstrate them! Include specific examples of how you've optimised backend systems or improved code quality in your previous roles. This will help us see your hands-on experience and technical excellence.
Communicate Clearly: Since we value clarity in communication, ensure your application is well-structured and easy to read. Use bullet points where necessary and avoid jargon unless it’s relevant to the role. We want to understand your thought process!
Apply Through Our Website: We encourage you to apply directly through our website. It’s the best way for us to receive your application and ensures you’re considered for the role. Plus, it shows you’re keen on joining our team at Koinly!
How to prepare for a job interview at Koinly
✨Know Your Ruby Inside Out
Make sure you brush up on your Ruby on Rails skills, especially around performance optimisation and system architecture. Be ready to discuss specific projects where you've improved code quality or system performance, as this will show your hands-on experience.
✨Understand the Crypto Tax Landscape
Familiarise yourself with the basics of crypto taxes and how they impact users. This knowledge will not only help you understand Koinly's mission but also allow you to engage in meaningful discussions about the challenges and solutions in this niche market.
✨Showcase Your Problem-Solving Skills
Prepare to discuss complex problems you've solved in previous roles, particularly those involving scaling systems or optimising data flows. Use the STAR method (Situation, Task, Action, Result) to structure your answers and highlight your impact.
✨Embrace the Async Culture
Since Koinly values async communication, be ready to demonstrate your ability to work independently and communicate clearly in writing. Share examples of how you've successfully collaborated in remote environments and how you manage your time effectively.
