Full Stack Engineer, Blockchain
Castle Island Ventures is a venture capital firm focused exclusively on public blockchains, investing in early-stage companies at the intersection of traditional finance and public blockchains.
About Castle Island Ventures
Castle Island Ventures is a venture capital firm focused exclusively on public blockchains. Their mission is to support entrepreneurs building the infrastructure and application companies required to help transformative blockchain protocols reach their full potential. They describe their focus as 'accelerating frictionless finance,' investing in early-stage companies operating at the intersection of traditional finance and public blockchains. The firm also produces a podcast and newsletter covering topics in this space, and maintains a portfolio of companies whose open roles are listed on their jobs board.
Skills
About the Role
You'll join a team building the backbone of on-chain access for some of the world's largest financial institutions and crypto-native organizations, working at the intersection of blockchain protocol engineering and enterprise-grade reliability. You will design systems that route, protect, and optimize transactions across dozens of chains at scale, and work on mission-critical infrastructure powering DeFi connectivity, multi-chain integrations, transaction execution pipelines, and on-chain data access. Your work will have a direct impact on how billions of dollars flow through decentralized networks every day.
Requirements
- 7+ years of experience as a Backend or Full Stack Engineer
- Bachelor of Science (B.Sc.) or equivalent degree/experience
- Blockchain and Web3 experience 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
Responsibilities
- 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
Benefits
- Meaningful equity