Software Development Engineer III, Fiat Payments (Backend)

About the company Our mission is that “Any financial application can onboard any user, anywhere in the world, in 1 click.” Transak provides onboarding to financial applications through authentication, KYC, risk checks, and fiat on/off ramps. This is a next generation of infrastructure for the next generation of financial applications that are built on blockchain and stablecoin rails. Our API and widget-based solutions are used by top partners like MetaMask, Coinbase, Ledger, and Trust Wallet to enable seamless onboarding of over 10 million users across over 450 active applications. We have raised over $37M from top-tier investors including Consensys, Tether, and Animoca Brands About the role Transak's Fiat/Payments team builds and operates the rails that move money between traditional banking systems and crypto — ACH, SEPA, Faster Payments, wires, virtual accounts, and card rails. As an SDE 3, you will own critical, high-throughput payment microservices end-to-end: design, build, scale, and operate systems that move real money for users across multiple currencies and jurisdictions, with US,UK/EU regulatory and global banking-partner requirements as a core part of the job. This is a senior individual-contributor role calibrated against SDE 3 / Senior Engineer, driving architecture decisions, mentoring engineers, and being the go-to owner for a payments domain, while staying hands-on in code daily. Key Responsibilities Payment Systems Ownership & Architecture Own payment microservices end-to-end — design, build, deploy, and operate Node.js services (orders, payment, reconciliation, virtual accounts, payout orchestration) handling real-time financial transactions at scale. Design for correctness and failure: idempotent, retry-safe, reconciliable systems where every transaction is traceable, auditable, and recoverable (partial failures, webhook replays, duplicate detection, distributed state machines). Architect for scale and resilience across a distributed microservices architecture; make service-boundary and build-vs-buy decisions; address root causes rather than symptoms. Banking & Partner Integrations Drive integrations with banking and payment partners (e.g. banking and card providers / risk providers) — API contracts, webhook handling, sandbox-to-production rollout, and reconciliation logic across multiple rails (ACH, SEPA, Faster Payments, wires). Work with Risk, Compliance on KYC, AML, and fraud-control touchpoints in the payment flow. Infrastructure, CI/CD & Operations Build and maintain CI/CD pipelines (Jenkins) — automated testing, blue/green or canary deployments, and rollback strategies for services that cannot tolerate downtime or data loss. Operate infrastructure on AWS (ECS/EKS, Lambda, SQS/SNS, RDS, CloudWatch); contribute to infra-as-code, monitoring, alerting, and on-call runbooks for payment-critical systems. Optimize the data layer: schema design and query performance in MongoDB,…