Backend Engineer, Solving en España, España

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Backend Engineer, Solving based in Spain.

As a Backend Engineer, Solving, you will develop and maintain the core systems that power fast, reliable, and cost-efficient cross-chain transactions. You will build the software responsible for generating quotes, optimizing trade routes, and executing user requests across on-chain and off-chain liquidity venues. Your work will directly influence transaction success rates, execution speed, pricing accuracy, and business profitability. Working primarily with TypeScript and https://jobeax.com/link/JSd7UYCSg572jJDY, you will tackle complex backend challenges across decentralized finance (DeFi), blockchain infrastructure, and payment systems. You will collaborate closely with protocol engineers to integrate new settlement mechanisms and advance decentralized liquidity solutions. This is a high-impact, hands-on role offering significant ownership, technical autonomy, and the opportunity to shape infrastructure that makes blockchain transactions more accessible.

Accountabilities

• Design, build, and continuously improve the core quote-generation and pricing engine, incorporating on-chain price feeds, swap routing integrations, and dynamic fee calculations to deliver competitive and reliable transaction execution.

• Develop and maintain integrations with decentralized exchanges (DEXs) and aggregators, including 1inch, LiFi, and Uniswap, implementing contract-level transaction calldata, multi-hop routing, slippage management, and gas estimation.

• Own end-to-end transaction pipelines, from deposit detection and quote generation through trade execution and settlement, ensuring reliable processing across complex, multi-stage workflows.

• Improve system reliability and operational visibility by implementing structured error propagation, monitoring, alerting, and incident-triage workflows using tools such as Datadog.

• Identify, investigate, and resolve execution failures and performance bottlenecks, accounting for transaction reverts, retry mechanisms, liquidity constraints, gas-price spikes, and other edge cases.

• Collaborate with protocol engineering teams to integrate new settlement primitives and support the transition toward decentralized, protocol-backed liquidity.

• Develop specialized transaction and pricing features for payment use cases, including one-to-one stablecoin transactions and fixed pricing for major assets.

• Take ownership of projects from initial design through implementation, testing, deployment, and ongoing optimization, ensuring that solutions meet performance, reliability, and business requirements.

• Contribute to the continuous improvement of backend architecture, engineering practices, and operational tooling to support a scalable and dependable cross-chain transaction infrastructure.

Requirements

• Strong backend engineering experience with TypeScript and https://jobeax.com/link/JSd7UYCSg572jJDY, including the ability to develop, maintain, and optimize production-grade backend services.

• Hands-on experience building systems that interact with on-chain protocols, including querying DEX quotes, constructing swap calldata, handling transaction reverts, and implementing retries or recovery mechanisms.

• Solid understanding of decentralized finance fundamentals, including automated market makers (AMMs), liquidity pools, token routing, slippage, price impact, and maximum extractable value (MEV).

• Demonstrated ability to design and own complex, multi-stage processing pipelines, connecting transaction detection, pricing, execution, and settlement into reliable end-to-end systems.

• Strong focus on reliability and resilience, with the ability to anticipate edge cases, implement robust error handling, establish meaningful observability, and troubleshoot production issues systematically.

• Excellent problem-solving and analytical skills, with the ability to navigate technical complexity, make sound engineering decisions, and balance execution performance, pricing, and reliability.

• A high degree of ownership and autonomy, including the ability to drive projects independently from concept to production, manage technical trade-offs, and take responsibility for outcomes.

• Effective communication and collaboration skills, with the ability to work across engineering teams, share technical context, and contribute to a collaborative, remote-first environment.

Nice to have

• Experience with cross-chain bridging protocols, blockchain interoperability, or intent-based architectures.

• Previous experience developing solver infrastructure, market-making systems, or other execution systems within decentralized finance.

• Familiarity with Solana and Jupiter routing, or with Bitcoin UTXO-based transaction models.

• Experience with BullMQ, Redis-backed job queues, or comparable asynchronous processing infrastructure.

• A proven track record of integrating with major DEX aggregators, such as 1inch, LiFi, or 0x.

• Experience designing systems that optimize transaction pricing, liquidity utilization, execution efficiency, and overall reliability.

Benefits

• Competitive base salary.

• Equity package, offering an opportunity to participate in the company's long-term growth.

• Comprehensive health benefits.

• Unlimited paid time off, with an encouraged minimum to support regular rest and work-life balance.

• Remote-first working environment that emphasizes flexibility, collaboration, and clear communication.

• Opportunity to work on high-impact blockchain infrastructure serving millions of users across multiple blockchain networks.

• Significant technical ownership and the opportunity to solve complex engineering challenges in cross-chain payments and decentralized finance.