Senior Java Software Engineer

Our client, a software vendor in the security space, is seeking a Senior Software Engineer to design, build and run high-traffic Java services, including the backend that integrates with SIM and eSIM-based security applets. This is a hands-on senior role: you’ll own features from design through on-call, set the standard for the engineers around you, and treat security as a design input rather than an afterthought.What you’ll doWrite production-ready code and own the pipeline and Helm chart that ship itBuild and integrate services that talk to SIM/eSIM applets, OTA platforms and mobile network operatorsProduce low-level designs other engineers can build from, and represent the team in architecture reviewsThreat-model each feature, with authentication, authorisation and data handling designed in from the startInstrument before release, take a turn on call, and drive faults to root causeSpot technical gaps early, propose each fix with a cost and benefit, and use AI tooling day to dayMentor engineers, hold the line on testing and error handling, and interview candidatesWhat you’ll bring8+ years with Java 17+, Spring Boot and Spring Security, and the ability to debug the JVM from thread dumps, heap dumps and tracesExperience designing and operating client-facing microservices, including API versioning and unit, integration, contract and load testingDesigning for failure and scale: idempotency, retries, circuit breakers, caching, and data-led bottleneck diagnosisStrong relational data modelling and query design (MySQL), with schema and index tuning proven under loadSolid security grounding: OWASP Top 10, authN/authZ, secrets managementKubernetes, Docker, Helm, AWS and CI/CD, including debugging failed deploymentsClear design writing and a habit of reviewing peers’ designsNice to have: JavaCard applet development for SIM, UICC/eUICC or secure elements; eSIM and Remote SIM Provisioning (RSP); OTA/AOTA platforms; telco/MNO integrations; reactive Java (WebFlux, Reactor, RxJava or Vert.x); OAuth 2.0, JWT, SAML, FIDO or WebAuthn; work in a regulated industry; SLIs/SLOs and error budgets; Kafka in production; Terraform