Senior Web3 Engineer Lisboa

Senior Web3 Engineer
Lisboa
Lisboa, Lisboa, Portugal

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About Block Labs

Block Labs is a leading force in the Web3 space, incubating, investing in, and accelerating
- tier fintech, crypto and i
Gaming projects. We aim to shape the future of decentralized technology by partnering with visionary startups to raise funding, refine
- market fit, and grow their audiences. Our diverse team drives innovation, leveraging industry expertise and a broad network to empower
- driven companies. We are passionate about turning bold ideas into breakthrough successes.

About The Role

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

We are developing a modular platform to facilitate secure SSO onboarding, dynamic routing, and
- time interactions with decentralized systems, bridging Web2 and Web3.

This role involves designing robust services that interface with external platforms, manage transactional integrity, and enable future products.

Key Responsibilities

• Design and implement backend services (JS/TS) interfacing with blockchains (EVMs, Solana, Bitcoin) and liquidity providers (e. g. , THORSwap, 0x, Uniswap).
• Build
  - onramp orchestration logic for
  - time selection of fiat→crypto providers based on fees, speed, and availability.
• Integrate Fireblocks MPC & Multi-Device Flow for secure transaction signing, key rotation, and delegated approvals.
• Develop
  - relay infrastructure (ERC-2771 / Biconomy or custom relayer) for seamless, gasless user transactions.
• Expose APIs (REST/Graph
  QL/JSON-RPC) for frontend and mobile teams; document contracts and edge cases.
• Write comprehensive unit and integration tests; monitor
  - chain events and
  - party SLAs.
• Stay updated on Ethereum/L2 roadmap items and suggest improvements.

About You

• Computer Engineer or similar degree.
• 5+ years backend or
  - level engineering; 3+ years blockchain integration experience (Ethereum, EVM L2s, or Solana).
• Strong coding skills in Go or Java
  Script/Type
  Script; familiarity with
  - contract ABIs.
• Experience with wallet/key-management solutions (Fireblocks, Web3Auth, Safe).
• Deep understanding of
  - chain transaction lifecycle, gas markets, nonce management, chain reorgs.
• Proven experience integrating
  - party APIs for swaps, bridges, or
  - /off-ramps; liquidity routing experience is a plus.
• Familiarity with web3 providers like Alchemy or Infura.
• Experience with Hardhat, Foundry, or Anchor.
• Knowledge of cryptographic primitives (ECDSA/MPC, EIP-1559, ERC-4337).
• Comfort with cloud environments (AWS, Ia
  C, CI/CD).
• Commitment to clean code, testability, and maintainability.
• Excellent English communication skills.

Nice-to-haves: Rust or Solidity smart contract development, experience with Oracles,
- source Web3 contributions, i
Gaming experience.

Seniority level

• Mid-Senior level

Employment type

• Full-time

Job function

• Other

Industries

• IT Services and IT Consulting

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