Senior Web3 Engineer

🏷️Title: Senior Web3 Engineer

👫Department: Engineering

📍Location: Remote within EU/UK

About Block Labs

Block Labs is a leading force in the Web3 space, incubating, investing in, and accelerating top-tier fintech, crypto and iGaming projects. With a mission to shape the future of decentralized technology, we partner with visionary startups to raise funding, refine product-market fit, and grow their audiences. Our diverse team drives innovation, using deep industry expertise and an extensive network to empower the next wave of blockchain-driven companies. At Block Labs, we’re passionate about turning bold ideas into breakthrough success.

About The Role

As our Web3 Integration Engineer, you will own the end-to-end integrations with blockchains, liquidity and swap aggregators, on-/off-ramp providers, and key-management platforms such as Fireblocks. Your work will power features like multi-onramp routing, gasless transactions, and deep on-chain analytics across our wallet, widget, and mobile products.

In line with our mission to bridge the Web2 to Web3 gap, we are developing a highly configurable, modular platform that powers secure SSO onboarding, dynamic routing, and real-time interactions with decentralized systems.

We are expanding our backend team with a focus on integrating critical third-party systems into our platform. This role is ideal for engineers who enjoy the complexity of designing robust services that interface with external platforms, manage transactional integrity, and act as strategic enablers for future products.

Key Responsibilities

• Design and implement backend services (JS/TS) that interface with multiple blockchains (EVMs, Solana, Bitcoin), and liquidity providers (e.g., THORSwap, 0x, Uniswap).
• Build multi-onramp orchestration logic that selects optimal fiat→crypto providers in real time based on fees, speed and chain availability.
• Integrate Fireblocks MPC & Multi-Device Flow for secure transaction signing, key rotation, and delegated approvals.
• Develop and maintain gas-relay infrastructure (ERC-2771 / Biconomy or custom relayer) to enable seamless, gasless user transactions.
• Expose clean, versioned REST/GraphQL/JSON-RPC APIs for frontend and mobile teams; document contracts and edge cases.
• Write robust unit and integration tests; set up heartbeat monitors against on-chain events and third-party SLAs.
• Stay current on Ethereum/L2 roadmap items (e.g., account abstraction, bridges, swaps) and propose actionable improvements.
  
  

About You

• Computer Engineer or equivalent University degree
• 5+ years backend or protocol-level engineering; 3+ years production work with blockchain integrations (Ethereum, EVM L2s, or Solana).
• Strong coding skills in Go or JavaScript/TypeScript; comfortable interacting with smart-contracts ABIs.
• Hands-on experience with one or more wallet/key-management solutions (Fireblocks, Web3Auth, Safe or similar).
• Deep understanding of on-chain transaction lifecycle, gas markets, nonce management, and chain reorg handling.
• Proven track record integrating third-party APIs for swaps, bridges, or on-/off-ramps; bonus for experience with liquidity routing algorithms.
• Familiarity with using web3 common providers like Alchemy or Infura.
• Familiarity with Hardhat, Foundry or Anchor
• Familiarity with cryptographic primitives (ECDSA/MPC, EIP-1559 fee model, ERC-4337 account abstraction).
• Comfort working in cloud-native environments—AWS, IaC, and modern CI/CD.
• Passion for clean code, testability, and long-term maintainability.
• Excellent written and verbal English communication
  
  

Nice-to-haves: Rust or Solidity smart contract development, experience with Oracles, prior contributions to open-source Web3 projects. iGaming experience.