Senior/Staff Smart Contract Engineer in London

About Symbiotic

Symbiotic is the infrastructure beneath collateral markets, where capital can secure financial obligations, remain productive, and be enforced by code. By changing the economics of onchain collateral, Symbiotic enables new categories of neofinance applications that were previously impossible to build - including credit, insurance, RWA liquidity, and more. As institutional capital increasingly moves onchain, Symbiotic is positioned to become the coordination layer connecting capital and risk across the onchain economy. Backed by Paradigm, Pantera, Cyber.fund, and Coinbase Ventures, we power 80+ vaults, 74,000+ active stakers, and 111 operators - with Chainlink, Nexus Mutual, and Cap Labs among the teams live in production.

Our People

We’re a tight-knit team of experienced builders working at the forefront of financial infrastructure. Our backgrounds span high-growth tech start-ups, leading crypto companies, major banks, insurers, and financial institutions. We work with ownership, a high bar for craft, and the urgency of an early-stage company - in an environment where people are trusted to take initiative and supported to do their best work. We’re looking for talented professionals to join us at a defining moment, as Symbiotic helps shape the next generation of onchain finance.

About the role

We're building on-chain collateral markets for both traditional and crypto-native finance. We're scaling our core protocol and the products built on top of it, and you'll work across our existing smart contract codebase — core contracts, core extensions, and middleware SDK — while building new modules from the ground up. Your work will span extending mature, in-production systems and architecting greenfield financial products designed and built from scratch on our stack.

What You'll Do

• Design, write, optimize, and audit smart contracts in Solidity, with a focus on performance, clarity, and security
• Build DeFi primitives from scratch — vaults, lending mechanics, staking, and related protocol-level components
• Develop adapters, connectors, and plugins for our Liquid Lane product across varying levels of complexity
• Contribute to the design and buildout of greenfield financial products.
• Conduct and support security audits, addressing vulnerabilities and hardening contracts against common attack vectors
• Where needed, build beyond the contract layer, leveraging AI as a multiplier: simple frontends, indexers, internal tooling, to move a piece of work end to end

Who You Are

• Expert in Solidity, with deep knowledge of EVM internals: execution flow, memory/storage models, gas mechanics, and precompiles
• Strong grasp of DeFi protocols and primitives — how lending protocols, DEXes, stablecoins, work, where they break, and the common pitfalls of building them
• Strong security mindset: familiar with common attack vectors, contract optimization, and the audit process
• Comfortable working across the stack when a task calls for it — you become a fullstack developer if the job requires it
• Solid computer science fundamentals — algorithms, low-level reasoning about how code executes

Nice to Have

• Deep specialist knowledge in one protocol domain, even if exposure to others is lighter — we value genuine depth/expertise
• Experience in compiler development
• Experience in Rust, Go, C/C++
• Practical coding experience in Python and JavaScript/TypeScript
• Exposure to Yul, Vyper, or Huff