Senior Software Engineer (Web3 Payments)

<p>We are supporting an APAC-focused technology company building a non-custodial, protocol-level payment infrastructure that enables seamless on-chain settlement for API-based services. The project sits at the intersection of Web3 payments, cryptographic verification, and high-reliability backend systems, with a strong emphasis on security, low latency, and production-grade operations.</p> <p>This is a greenfield build where senior engineers will help define architecture, security models, and operational standards from day one.</p> <p>As a Senior Software Engineer, you will take ownership of core backend services that verify cryptographically signed payment requests and coordinate on-chain settlement across multiple blockchain networks. You will work closely with security, compliance, and product stakeholders, and play a key role in shaping system design, reliability practices, and developer experience.</p> <p><strong>Responsibilities</strong></p> <ul> <li>Design and implement high-performance backend APIs for payment verification and settlement</li> <li>Build cryptographic verification logic (signature validation, replay protection, idempotency)</li> <li>Integrate with blockchain RPC providers and design confirmation, retry, and failover strategies</li> <li>Architect secure key-management solutions (KMS/HSM), audit logging, and least-privilege access</li> <li>Develop chain adapters for EVM and non-EVM networks, starting with stablecoin transfers</li> <li>Own production readiness: SLOs, monitoring, alerting, and incident response workflows</li> <li>Write technical documentation, threat models, and operational runbooks</li> <li>Mentor junior engineers and contribute to engineering standards and best practices</li> </ul> <p><strong>Qualifications</strong></p> <ul> <li>5–8+ years of backend engineering experience, ideally in TypeScript/Node and/or Rust</li> <li>Strong understanding of cryptographic signatures, structured payloads, and API security</li> <li>Hands-on experience with EVM transaction lifecycle (nonce, gas, finality) and/or Solana</li> <li>Proven track record building production-grade distributed systems</li> <li>Experience with CI/CD, containerised deployments, and observability tooling</li> <li>Excellent written communication skills (design docs, threat models, runbooks)</li> </ul> <p><strong>Strongly Preferred</strong></p> <ul> <li>Experience with payment or settlement systems (idempotency, retries, reconciliation)</li> <li>Familiarity with stablecoin transfer patterns (e.g. USDC on EVM chains)</li> <li>Background in non-custodial architectures or security-sensitive systems</li> <li>Exposure to protocol-level payment flows, API monetisation, or metered billing</li> </ul>