Senior Software Engineer, Blockchain

1Inch

1Inch

Software Engineering

Spain

Posted 6+ months ago
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1inch is the DeFi ecosystem building financial freedom for everyone. 1inch products help users and builders trade, hold and track digital assets - with the self-custody, comprehensive security and the intuitive user experience they need to unlock the potential of true crypto ownership. 1inch protocols and APIs provide core infrastructure across the DeFi industry and beyond.

Your mission

As a Senior Software Engineer, Blockchain at 1inch, you will help design, build, and optimise the smart contracts and blockchain infrastructure powering one of the leading DeFi ecosystems. Working closely with product and engineering leadership, you will contribute to scalable, secure, and high-performance decentralised systems that support millions of users globally.

This role combines deep technical expertise with a strong product and innovation mindset, requiring hands-on experience across smart contract development, blockchain architecture, and protocol security. You will play a key role in advancing cross-chain interoperability, improving execution efficiency, and maintaining engineering excellence across the development lifecycle while contributing to the evolution of cutting-edge Web3 infrastructure.

What you’ll do

  • Design and optimise blockchain architectures with a strong focus on scalability, security, and performance
  • Develop, integrate, and maintain smart contracts across decentralised protocols and infrastructure components
  • Conduct technical research and build proof-of-concepts for new DeFi and blockchain innovations
  • Design and improve cross-chain interoperability solutions, including bridging and atomic swap mechanisms
  • Optimise smart contract execution efficiency with a focus on gas consumption and low-latency performance
  • Collaborate with internal and external security auditors to identify vulnerabilities and strengthen protocol security
  • Lead code reviews and contribute to engineering best practices, CI/CD workflows, and development standards
  • Mentor junior and mid-level engineers while contributing to a collaborative engineering culture

Who you are

  • 7+ years of professional software engineering experience, including 3+ years focused on blockchain development
  • Deep expertise in Ethereum and EVM ecosystems, including Solidity, Yul, and decentralised application architecture
  • Strong experience building and deploying smart contracts in production environments
  • Hands-on experience with Layer 2 scaling solutions and cross-chain infrastructure
  • Proven ability to drive architectural decisions and lead complex technical initiatives from design to deployment
  • Strong understanding of smart contract security principles, auditing processes, and vulnerability mitigation
  • Experience working in fast-paced, high-growth engineering environments
  • Strong problem-solving skills with a proactive, ownership-driven mindset

Nice to haves

  • Experience contributing to open-source blockchain or DeFi projects
  • Familiarity with zero-knowledge technologies and rollup architectures
  • Experience building high-performance distributed systems or low-latency infrastructure
  • Understanding of DeFi protocols, liquidity aggregation, or on-chain trading systems
  • Knowledge of Web3 developer tooling and blockchain infrastructure automation
1inch is an equal opportunity employer. We are committed to evaluating all candidates on the basis of their skills, experience, and potential — regardless of race, ethnicity, nationality, gender, age, religion, disability, or any other characteristic. We believe diverse teams build better products, and we welcome applications from all backgrounds.
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