Senior Backend Engineer – Finapps/Access

Location: Warszawa, Masovian Voivodeship, Poland

Department: R&D

 

About Fireblocks

Fireblocks is on a mission to enable every business to easily and securely access digital assets and cryptocurrencies. As a leading provider in the digital asset space, we are committed to fostering a diverse and inclusive workforce that mirrors the global clientele we serve.

About the Team

The FinApps Access team at Fireblocks builds the backbone of on-chain access for some of the world's largest financial institutions and crypto-native organizations. We operate at the intersection of blockchain protocol engineering and enterprise-grade reliability — designing systems that route, protect, and optimize transactions across dozens of chains at scale.

You'll work on mission-critical infrastructure powering DeFi connectivity, multi-chain integrations, transaction execution pipelines, and on-chain data access — with direct impact on how billions of dollars flow through decentralized networks every day.

What You'll Do

• Design and build robust, scalable backend services supporting high-volume on-chain transaction flows across multiple blockchain networks — both EVM and non-EVM.
• Own end-to-end development of backend components and APIs — from architecture decisions to production deployment.
• Lead integrations with DeFi protocols, on-chain data sources, and blockchain nodes across a wide range of chains and ecosystems.
• Research and evaluate emerging blockchain technologies, protocols, and standards to keep Fireblocks at the cutting edge.
• Optimize existing production systems for performance, reliability, and security — reducing latency and increasing throughput.
• Collaborate closely with product, protocol research, and platform engineering teams to deliver high-quality solutions on time.
• Drive features from inception through to delivery at scale, taking full ownership of the product lifecycle.

What You'll Bring

• 7+ years of experience as a Backend or Full Stack Engineer.
• Bachelor of Science (B.Sc.) or equivalent degree/experience.
• Blockchain and Web3 experience are a must — including deep understanding of transaction lifecycles, consensus mechanisms, smart contract interactions, and on-chain data.
• Proven experience working across multiple blockchain ecosystems — EVM-compatible chains (Ethereum, Polygon, Arbitrum, Base, etc.) as well as non-EVM chains such as Solana, TON, Tron, or similar.
• Proficiency in Node.js and TypeScript.
• Experience designing and operating microservices in production CI/CD environments.
• Strong understanding of security principles, cryptography, and best practices in a blockchain context.
• Familiarity with DeFi protocols — AMMs, lending markets, bridging infrastructure, or on-chain routing — is a strong advantage.
• Experience with Web3 tooling and libraries (ethers.js, viem, web3.js, Solana web3.js, etc.).
• Demonstrated experience taking products from inception to delivery at scale.
• Full stack experience (React, frontend development) — a nice to have.

About You

• You think in systems and care deeply about correctness, reliability, and scale.
• You're comfortable navigating ambiguity and can drive technical decisions with limited oversight.
• You have a natural curiosity for how blockchain protocols work under the hood — and you actually read the specs.
• You thrive in fast-moving environments and can balance shipping velocity with long-term code quality.
• You communicate clearly and collaborate effectively across engineering, product, and research.

Why Fireblocks

• Work at the frontier of blockchain infrastructure, with real impact on how DeFi scales for institutional and retail users.
• Tackle genuinely hard engineering problems — multi-chain routing, on-chain data indexing, protocol integrations, and more.
• Collaborate with world-class engineers, protocol researchers, and product minds in a fast-growing global company.
• Competitive compensation, meaningful equity, and a culture that rewards ownership and initiative.

For employees hired to work from Poland, the estimated compensation range for this role is PLN 300,000 – 3800,000 gross annually. It is not typical for a candidate to be hired at or near the top of the pay range and each compensation decision is dependent on each individual case. The base salary is one component of the total compensation package, which for some roles may include a target bonus, a very competitive equity grant, and very generous benefits. While we believe competitive compensation is a critical aspect of you deciding to join us, we do hope you also spend time considering why our mission and culture are right for you. We are creating something transformational here, and we hope you are as excited about the future as we are.