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Salary: USD 150,000 - 230,000 / annual
0x is a web3 infrastructure company on a mission to create a tokenized world where all forms of value can flow freely. Founded in 2017, the company has processed 211M+ transactions and $180B+ in trading volume across major wallets and exchanges including Coinbase Wallet, Robinhood Wallet, Phantom, Rainbow, MetaMask, and others. Backed by Greylock Partners, Pantera Capital, and Jump Crypto, 0x is a veteran team focused on code quality, team cohesion, and continuous learning.
The API Products team is a four-person group responsible for building and maintaining 0x's flagship Swap, Gasless, and Cross-Chain APIs that have moved billions in volume. The team integrates hundreds of liquidity sources, optimizes for gas, slippage, and latency, and simulates every trade to deliver the best possible outcomes for traders.
As a Senior Software Engineer on this team, you will lead projects from conception to production on both new products and existing live APIs. This is a hands-on individual contributor role with real ownership, working closely with the product team and major customers. You'll have significant autonomy and work well with minimal direction.
Key responsibilities include: building new APIs and trading products from problem research through architecture design to shipping; maintaining and extending existing APIs with support for new chains, bridges, and customer-requested features; ensuring APIs remain fast and reliable as traffic scales, including on-call rotation participation; investigating failed trades and stuck transfers using logs, traces, and onchain data to resolve root causes; collaborating with product, legal, and go-to-market teams to translate business and compliance needs into technical decisions; and writing design documents and reviewing teammates' work.
You will work in EU timezones with flexibility for a fully remote setup. The role includes attendance at annual in-person team offsites around the globe.
REQUIREMENTS:
- 6+ years of backend engineering experience, with at least 2 years in DeFi (at a trading app, wallet, DEX aggregator, onchain data company, or similar)
- Senior or Lead Engineer track record with demonstrated ownership of complex end-to-end projects
- Experience building and maintaining developer-facing APIs
- Deep onchain knowledge, especially EVM: transactions, calldata, contract interfaces, gas, and approvals
- Strong system design experience for production-scale backend services
- Proficiency using AI tools to multiply engineering impact without replacing judgment
- Clear communication skills, comfortable explaining technical tradeoffs to non-technical stakeholders
- Alignment with core values: do the right thing, consistently ship, focus on long-term impact
- Ability to attend annual in-person team offsites globally
Nice to have: cross-chain/bridging or DEX aggregation experience; experience with non-EVM ecosystems like Solana; TypeScript and/or Rust experience.
