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APEXX Global is an independent, enterprise payment orchestration platform that enables merchants to connect once and access the world's payment ecosystem—acquirers, alternative payment methods (APMs), Buy Now Pay Later (BNPL) providers, and network tokenization. The company's routing engine (AIRE) makes millisecond decisions to maximize acceptance and minimize cost. APEXX is backed by MMC, Forward Partners, Alliance VC, and Finch Capital, and serves enterprise travel and ecommerce merchants including Jet2, TUI, Ryanair, CarTrawler, and Hotelbeds.
As a Senior Backend Software Engineer on the Platform Engineering team, you will own core payment flows end-to-end—authorization, capture, refund, void, and MIT/recurring transactions across card and APM rails, from design through production and beyond. You'll evolve routing and recovery logic (rules-based and data-driven routing, decline cascading, Smart Split, outage failover) to ensure retries never become double charges. You'll build and maintain connectors to acquirers, APMs, and BNPL providers, normalizing responses and handling API version drift and partner outages.
You'll design for correctness under failure: idempotency, timeouts, ambiguous payment states, asynchronous notifications, webhooks, and reconciliation against settlement files. You'll protect cardholder data within tokenization and vault services, HSM-backed cryptography, and PCI DSS/SOC 2/ISO 27001 controls. You'll run the platform by joining the on-call rotation, defining and tracking SLOs, writing runbooks, leading incidents, conducting blameless RCAs, and improving GitLab CI/CD and AWS infrastructure (ECS, Lambda, API Gateway, S3). You'll raise the bar through technical design docs, high-quality code reviews, mentoring, and helping modernize the stack (Java 17, Spring Boot). You'll work cross-functionally with Product, Solutions, Support, and UK colleagues to turn merchant and partner needs into reliable systems.
REQUIREMENTS:
- Significant production experience building and running backend services in Java and Spring Boot, or comparable JVM/backend stack with willingness to transition to APEXX's stack
- Strong grasp of distributed-systems failure modes: retries, idempotency, timeouts, concurrency, eventual consistency, and reasoning about ambiguous states
- Solid PostgreSQL skills (schema design, transactions, isolation, query tuning) and practical Redis or similar cache experience
- Hands-on AWS experience and comfort with CI/CD, containers, and infrastructure-as-code
- Proven track record owning production services: on-call, debugging with logs/metrics/traces, leading incidents, writing RCAs
- Clear written communication: design docs, runbooks, RCAs, merge request descriptions
- Productive and critical use of AI coding tools; ability to verify output with tests and review before shipping
- Ability to help teammates improve through review, pairing, and mentoring
NICE TO HAVE:
- Payments experience: card acquiring, 3DS2/SCA, network tokens, APMs/BNPL, settlement, reconciliation, or payment orchestration
- Working knowledge of PCI DSS, HSMs, key management, OAuth2, or mTLS for partner integrations
- Observability tooling, SLO-based alerting, or analytics stacks (Snowflake, QuickSight)
- Scale-up or Fintech experience working with UK or global teams
