Senior Software Engineer (Web3 Payments)

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. This is a greenfield build where senior engineers will help define architecture, security models, and operational standards from day one. 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. Responsibilities Design and implement high-performance backend APIs for payment verification and settlement Build cryptographic verification logic (signature validation, replay protection, idempotency) Integrate with blockchain RPC providers and design confirmation, retry, and failover strategies Architect secure key-management solutions (KMS/HSM), audit logging, and least-privilege access Develop chain adapters for EVM and non-EVM networks, starting with stablecoin transfers Own production readiness: SLOs, monitoring, alerting, and incident response workflows Write technical documentation, threat models, and operational runbooks Mentor junior engineers and contribute to engineering standards and best practices Qualifications 5–8+ years of backend engineering experience, ideally in TypeScript/Node and/or Rust Strong understanding of cryptographic signatures, structured payloads, and API security Hands-on experience with EVM transaction lifecycle (nonce, gas, finality) and/or Solana Proven track record building production-grade distributed systems Experience with CI/CD, containerised deployments, and observability tooling Excellent written communication skills (design docs, threat models, runbooks) Strongly Preferred Experience with payment or settlement systems (idempotency, retries, reconciliation) Familiarity with stablecoin transfer patterns (e.g. USDC on EVM chains) Background in non-custodial architectures or security-sensitive systems Exposure to protocol-level payment flows, API monetisation, or metered billing Offices: Taiwan (Taiwan);