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Senior Smart Contract Engineer - DeFi Protocol Architecture

X-Team United State
Remote
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AI Summary

Build and scale secure on-chain infrastructure for next-gen open finance. Design, implement, and battle-test critical smart contracts managing significant TVL. Lead protocol architecture from design to mainnet deployment and audits.

Key Highlights
Fully remote role with meaningful overlap with US/EU working hours
4+ years of software engineering with 2+ years in secure Solidity smart contracts
Deep expertise in DeFi primitives, EVM internals, and security-focused testing
Key Responsibilities
Design and implement secure, gas-optimized Solidity smart contracts for lending, borrowing, vaults, yield routing, liquidations, and access control
Write extensive unit, integration, fork, fuzz, and invariant tests to ensure zero-day resiliency
Prepare codebases for top-tier external audits, remediate findings, and design proactive on-chain risk mitigation strategies
Collaborate with risk, frontend, indexer, and quantitative engineering teams to build seamless, secure end-to-end dApps
Take deep ownership of smart contract architecture from initial mathematical modeling through mainnet deployment and live monitoring
Technical Skills Required
Solidity Foundry (Forge, Cast) EVM Internals
Benefits & Perks
Fully remote work
Meaningful overlap with US/EU working hours
Nice to Have
Prior experience guiding a protocol through a major external audit (e.g., Trail of Bits, OpenZeppelin, Spearbit)
Exposure to Rust-based smart contract environments (SVM/Solana, CosmWasm) or zero-knowledge (ZK) rollup architectures
Familiarity with off-chain automation infrastructure like Keepers, Defender, or Gelato

Job Description


This role is a full-time engagement with the client, fully remote. Open to LATAM, USA & Canada.


The Mission

Help build and scale the secure on-chain infrastructure powering the next generation of open finance. In this role, you’ll design, implement, and battle-test critical smart contracts that manage significant TVL and capital-efficient primitives. This isn't about deploying speculative tokens; it’s about constructing highly resilient, mathematical, and adversarial-resistant software that remains upgradeable, cost-efficient, and bulletproof over time.


The Role

As a core protocol contributor, you will take deep ownership of smart contract architecture from initial mathematical modeling and design through to mainnet deployment, external audit facilitation, and live monitoring.

• Protocol Architecture (40%): Design and implement secure, gas-optimized Solidity smart contracts for lending, borrowing, vaults, yield routing, liquidations, and access control.

• Testing & Simulation (30%): Write extensive unit, integration, fork, fuzz, and invariant tests utilizing modern frameworks to ensure zero-day resiliency.

• Security & Audits (15%): Prepare codebases for top-tier external audits, remediate findings, and design proactive on-chain risk mitigation/monitoring strategies.

• Cross-Functional Integration (15%): Collaborate closely with risk, frontend, indexer, and quantitative engineering teams to build seamless, secure end-to-end dApps.


The Must-Haves

• Experience: 4+ years of professional software engineering experience, with at least 2+ years writing, deploying, and maintaining highly secure Solidity smart contracts in production..

• Tooling & Frameworks: Expert-level mastery of Foundry (Forge, Cast) including advanced fuzzing, invariant testing, and mainnet fork simulations.

• EVM Deep Dive: Thorough understanding of EVM internals, storage layouts, gas optimization strategies, assembly (Yul), and standard proxy/upgradeability patterns.

• DeFi Primitives: Practical, working knowledge of core financial primitives (such as ERC-20/4626/721/1155, AMMs, lending pools, oracles, and liquidation engines).

• AI-Assisted Acceleration: Comfort using modern AI coding tools (e.g., Cursor, Claude, Copilot) to accelerate unit testing, documentation, and boilerplate development, backed by the critical judgment required never to trust raw model outputs blindly.

• Security Mindset: An obsessive awareness of common attack vectors (reentrancy, oracle manipulation, front-running, rounding errors, and access-control flaws).


The Bonus Skills

• Audit Pedigree: Prior experience guiding a protocol through a major external audit (e.g., Trail of Bits, OpenZeppelin, Spearbit) or participating in competitive security audits.

• Multi-Chain/SVM: Exposure to Rust-based smart contract environments (SVM/Solana, CosmWasm) or zero-knowledge (ZK) rollup architectures.

• Advanced Automation: Familiarity with off-chain automation infrastructure like Keepers, Defender, or Gelato.


Personal Traits

• Adversarial Thinker: You don't just think about how code should work; you instinctively try to find ways to break, front-run, or exploit the state machine you are building..

• Execution & Ownership: You act as an owner, not a ticket executor. You proactively trace edge cases, optimize gas, and address technical debt before it is flagged..

• Detail-Obsessed: You care about the nuance of a single uint256 math operation and understand why rounding down vs. up is a security-critical decision..

• Collaborative & Clear: You can distill complex cryptographic or financial system logic into clear documentation and explain architectural tradeoffs to non-smart contract engineers..

Location: Remote (with meaningful overlap with US/EU working hours)


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