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- Tasks: Design and optimise scalable backend systems for processing billions of financial transactions.
- Company: Join Koinly, a profitable startup transforming crypto tax for millions.
- Benefits: Enjoy 32 days of PTO, flexible schedules, and a culture of autonomy.
- Why this job: Make a real impact in the fintech space with cutting-edge Ruby technology.
- Qualifications: 7+ years of backend experience with Ruby on Rails and strong communication skills.
- Other info: Work remotely in a small team with big ambitions and zero bureaucracy.
The predicted salary is between 72000 - 84000 ÂŁ per year.
Get AIâpowered advice on this job and more exclusive features. 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, highâperformance engineering.
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.
- Location: Remote â preference for Europeâbased candidates.
- Salary: USD $100Kâ115K / year.
- Contract type: Fullâtime (B2B contractor).
- Perks: 32 days of PTO, async culture, flexible workâschedule, culture of high autonomy and ownership.
- Experience level: 7+ years.
- Start date: ASAP.
- Team size: 10âperson engineering team.
Main responsibility: Engineer and optimize highâperformance Ruby systems that handle billions of financial transactions, solving deep scaling, data, and codeâquality challenges.
As Koinly scales, we need our backend systems to stay fast, reliable, and accurate. This Staff Engineer will provide handsâon 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 handsâon 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 crossâteam initiatives.
- Proven record improving system performance and code quality.
- Strong understanding of data flows and software design principles.
- Experience working crossâfunctionally in async, remote environments.
- Clear communication and ownership mindset.
Bonus:
- Experience tuning Postgres in production.
- Built or optimized data ingestion or reconciliation pipelines.
- Openâsource 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, wellâstructured systems, and clean code.
- Asyncâfirst 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 hyperâgrowth industry.
- Pure Ruby backend: no language sprawl or overâengineering.
- Autonomyâfirst: async communication, deep work, minimal meetings.
- Massive scale: billions of trades and 950+ integrations.
- Small team, big impact: millions of users, ~37 people companyâwide.
- No corporate theatre: zero bureaucracy, high trust, high ownership.
- Flexible by default: fully remote, async, and resultsâoriented.
- Cryptoâadjacent 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 London employer: Koinly
Contact Detail:
Koinly Recruiting Team
StudySmarter Expert Advice đ¤Ť
We think this is how you could land Staff Software Engineer in London
â¨Tip Number 1
Network like a pro! Reach out to folks in the industry, especially those already at Koinly. A friendly chat can give you insights and maybe even a referral, which can really boost your chances.
â¨Tip Number 2
Show off your skills! If youâve got a GitHub or portfolio, make sure itâs up to date with your best Ruby projects. This is your chance to demonstrate your expertise and passion for backend systems.
â¨Tip Number 3
Prepare for the interview by brushing up on system design and performance optimisation. Think about how youâd tackle scaling challenges and be ready to share your thought process during the chat.
â¨Tip Number 4
Donât forget to apply through our website! Itâs the best way to ensure your application gets seen by the right people. Plus, it shows youâre serious about joining the Koinly team!
We think you need these skills to ace Staff Software Engineer in London
Some tips for your application đŤĄ
Tailor Your CV: Make sure your CV is tailored to the Staff Software Engineer role. Highlight your Ruby on Rails experience and any projects where you've optimised performance or simplified complex systems. We want to see how your skills align with our mission at Koinly!
Craft a Compelling Cover Letter: Your cover letter is your chance to shine! Share your passion for backend engineering and how you can contribute to our team. Mention specific experiences that demonstrate your ability to handle high-performance systems and your approach to collaboration.
Showcase Your Projects: If you've worked on relevant projects, donât hesitate to showcase them! Whether it's open-source contributions or personal projects, we love seeing real examples of your work. This gives us insight into your coding style and problem-solving abilities.
Apply Through Our Website: We encourage you to apply directly through our website. Itâs the best way to ensure your application gets the attention it deserves. Plus, it shows us you're keen on joining our awesome team at Koinly!
How to prepare for a job interview at Koinly
â¨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.
â¨Understand the Crypto Landscape
Familiarise yourself with the basics of cryptocurrency and how tax systems work in this space. Being able to speak knowledgeably about Koinly's mission and how your role fits into simplifying crypto taxes will demonstrate your genuine interest in the company.
â¨Prepare for Technical Challenges
Expect to tackle some technical problems during the interview. Practice coding challenges that focus on backend systems and data flows, as well as discussing your thought process clearly. This will showcase your problem-solving skills and ability to communicate effectively.
â¨Show Your Collaborative Spirit
Koinly values teamwork and clear communication, especially in a remote setting. Be prepared to share examples of how you've collaborated with cross-functional teams and mentored other engineers. Highlighting your ownership mindset and how you drive projects from start to finish will resonate well.