Senior Backend Engineer

TechFlow is a Series B fintech building the next generation of payment infrastructure for European businesses. Backed by Accel and Index Ventures, the platform processes over £2 billion in annual transaction volume — and that number is doubling year on year.

As a Senior Backend Engineer, you'll take ownership of core payment processing microservices that handle millions of daily transactions across multiple currencies. You'll work in a small, high-trust squad alongside a Staff Engineer and a Principal Architect, shipping production code to real merchants within your first fortnight.

The stack is modern and deliberate: Go services on Kubernetes, event-driven architecture with Kafka, PostgreSQL for transactional data, and a strong emphasis on observability via OpenTelemetry and Grafana. You won't inherit legacy — you'll be building greenfield systems designed for 10x scale.

This is a hybrid role based out of TechFlow's London Bridge office, with the team typically in three days a week. Compensation includes base salary, meaningful equity, and a transparent progression framework.

• Design, build, and operate high-throughput payment processing services handling 5,000+ transactions per second with sub-100ms latency targets
• Own the full lifecycle of backend services — from RFC and architecture review through to deployment, monitoring, and incident response
• Collaborate with product and compliance teams to implement PSD2, SCA, and PCI-DSS requirements without compromising developer velocity
• Evolve the event-driven architecture — defining schema contracts, managing Kafka topic topology, and ensuring exactly-once processing guarantees
• Contribute to platform reliability through chaos engineering, load testing, and runbook development — targeting 99.99% uptime SLAs
• Mentor mid-level engineers through code review, pairing sessions, and technical design discussions
• Participate in a lightweight on-call rotation (1 week in 6) with strong tooling and escalation support

Essential

• 5+ years of professional backend engineering experience, with at least 2 years working in Go (or a strong systems language like Rust or C++ with demonstrable Go interest)
• Deep understanding of distributed systems patterns — eventual consistency, idempotency, circuit breakers, saga orchestration
• Production experience with message brokers (Kafka, RabbitMQ, or similar) and relational databases (PostgreSQL preferred)
• Comfortable operating containerised services in Kubernetes — you don't need to be a cluster admin, but you should understand pods, deployments, and resource management
• Strong testing discipline — unit, integration, and contract testing as part of your everyday workflow
• Excellent written communication skills — TechFlow runs on RFCs and async decision-making

Nice to Have

• Previous experience in payments, fintech, or regulated industries
• Familiarity with observability tooling — OpenTelemetry, Grafana, Prometheus, or Datadog
• Experience with CI/CD pipelines (GitHub Actions, ArgoCD) and infrastructure-as-code (Terraform)
• Contributions to open-source projects or technical writing