Transak

Software Development Engineer III, Fiat Payments (Backend)

Full-Time in London, GB - Engineering

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

1. 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.
2. 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.
3. 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, caching and rate-limiting strategies with Redis, and safe migration patterns for high-volume transactional collections.
   • Participate in on-call for payment-critical services, including incident response and postmortems.
4. Technical Leadership & Collaboration
   • Lead technical roadmaps — break down large, ambiguous payments initiatives into shippable milestones; write design docs/RFCs; drive consensus across Engineering, Product, Risk, and Operations.
   • Mentor and raise the bar — review code and designs, coach mid-level engineers, and help hire and grow the team.
   • Uphold security and compliance best practices for handling PII/financial data in a regulated, PCI-DSS-adjacent environment.

What We're Looking For

• 6+ years of professional software engineering experience, with a significant portion building backend/distributed systems; prior experience in fintech, payments, on-and-offramp provider, or banking infrastructure strongly preferred.
• Strong hands-on expertise in Node.js (TypeScript preferred) for performant, production-grade backend services.
• Deep experience with MongoDB — schema design, aggregation pipelines, indexing strategy, and performance tuning at scale.
• Proficiency with Redis — caching, distributed locks, rate limiting, and pub/sub patterns.
• Proven experience designing and operating microservices architectures, including inter-service communication (REST/gRPC/event-driven via SQS/Kafka,ELK,New relic, Mixpanel), service discovery, and API contract design.
• Solid understanding of CI/CD pipelines, with hands-on experience using Jenkins (pipeline-as-code, multi-stage builds, automated test gates).
• Working knowledge of AWS infrastructure — ECS/EKS/Lambda, VPC networking basics, IAM, S3, RDS, CloudWatch; infra-as-code (Terraform/CloudFormation) is a plus.
• Strong grasp of distributed systems fundamentals: idempotency, eventual consistency, retries/backoff, circuit breaking, and failure isolation.
• Track record of owning a service or domain end-to-end in production, including on-call responsibility.
• Excellent written communication — comfortable authoring design docs/RFCs and explaining trade-offs to engineers and non-technical stakeholders (Risk, Ops, external partners).

Nice-To-Haves

• Experience with payment rails (ACH, SEPA, Faster Payments, SWIFT/wires) or card processing.
• Familiarity with banking partner integrations, webhook-driven reconciliation, or ledger/double-entry accounting systems.
• Exposure to KYC/AML/fraud tooling.
• Experience at a fintech/crypto-native company, payments processor, or Big Tech payments org.
• Prior experience operating in a regulated environment (FCA, EMI/PI licensing context), given the UK/EU banking scope of this role.