Senior Software Engineer, API Products

0x is building infrastructure for a tokenized world where all forms of value can move freely. Founded in 2017, the company has processed over 211 million transactions and $180 billion in trading volume through developer APIs integrated into leading wallets and exchanges including Coinbase Wallet, Robinhood, MetaMask, and Phantom. With backing from Greylock Partners, Pantera Capital, and Jump Crypto, 0x attracts experienced crypto builders committed to code quality and continuous learning.

The API Products team sits at the heart of 0x's platform. They integrate hundreds of liquidity sources, optimize for gas efficiency and slippage, and route trades to deliver the best outcomes. This small team of four maintains and evolves flagship products like the Swap, Gasless, and Cross-Chain APIs that have moved billions in volume, while building new capabilities for developers building trading applications.

0x is hiring a Senior Software Engineer to expand the API Products team's capacity. In this hands-on individual contributor role, you'll own projects from conception through production, working on new product development and enhancing existing APIs that serve some of the company's largest customers. You'll operate with real ownership and autonomy, partnering closely with product, legal, and go-to-market teams.

What you'll do

• Design and build new APIs and trading products from problem research through initial release, as well as maintain and extend existing APIs with support for new chains and customer features.

• Ensure API performance and reliability as transaction volume scales, participating in on-call rotations and investigating failed trades using logs, traces, and onchain data to resolve root causes.

• Translate business, compliance, and product requirements into technical solutions through collaboration with non-engineering teams.

• Author technical design documents and provide thorough code review and design feedback to teammates.

What you'll bring

• Six or more years of backend engineering experience with at least two years working in DeFi at a trading app, wallet, DEX aggregator, or similar company.

• Proven track record as a Senior or Lead Engineer owning complex projects end to end with deep experience building and maintaining developer-facing APIs.

• Strong knowledge of EVM blockchains including transaction mechanics, calldata, contract interfaces, gas optimization, and approval patterns.

• Demonstrated expertise in system design for production-scale backend services.

• Proficiency using AI tools to enhance engineering productivity while maintaining sound technical judgment.

• Ability to communicate technical tradeoffs clearly to non-technical stakeholders and commitment to 0x's core values: do the right thing, consistently ship, and focus on long-term impact.

Nice to have

• Experience with cross-chain bridges or DEX aggregation protocols.

• Familiarity with non-EVM ecosystems such as Solana.

• Proficiency in TypeScript or Rust.

What they offer

• Base salary of USD $150,000 to $230,000 plus equity and ZRX tokens, with individual compensation determined by experience, skills, and location.

• Comprehensive medical, dental, vision, life, and disability insurance for U.S. employees with 100% of base plan covered for you and dependents, plus 401k and FSA.

• Mental health benefits including covered professional therapy sessions, monthly mobile phone reimbursement, wellness stipend, and remote workspace setup allowance.

• Twelve weeks paid parental leave, flexible vacation policy, and lunch reimbursement globally.