Java Software Engineer (Contract Outside of IR35)

📋 Description

• • Shape the security backbone of government-grade systems as a Java Software Engineer at TwinStream, a consultancy born from engineers who once solved the toughest cross-domain challenges inside government organisations themselves. Since 2019 we have channelled that first-hand experience into a remote-first culture where autonomy, technical rigour and real-world impact converge.
• • Own the full SDLC for components of a cross-domain security platform that protects sensitive data flowing between classified and open networks. You will move fluidly from white-boarding high-level requirements with security architects to writing defensive Java code that stands up to hostile scrutiny.
• • Translate abstract security policies into concrete micro-services, message queues and zero-trust APIs. Every line you commit directly influences how safely information can be shared across military, intelligence and civilian departments.
• • Investigate emerging technologies—hardware security modules, confidential computing runtimes, post-quantum crypto libraries—and run spike experiments to prove (or disprove) their suitability for classified environments. Your findings steer architectural decisions that last for years.
• • Engineer for resilience: design idempotent workflows, graceful degradation patterns and circuit-breakers that keep the system alive when networks partition or threats spike. Pair with DevOps specialists to codify these patterns in Terraform, Helm and GitHub Actions pipelines.
• • Build exhaustive test pyramids: JUnit 5 property-based tests, contract tests with Pact, performance benchmarks with Gatling, and security-focused acceptance tests executed inside containerised test rigs that mirror production classification levels.
• • Tackle 3rd-line support tickets that reach beyond typical application bugs—think TLS handshake anomalies, JVM garbage-collection pauses under classified load, or subtle race conditions in concurrent secret rotation. Your deep dives often become knowledge-base articles that level-up the whole team.
• • Collaborate daily through remote-first ceremonies: story mapping, mob-programming sessions, architecture katas and blameless post-mortems. We default to video, Miro and pair-programming in IntelliJ to keep context rich despite physical distance.
• • Contribute to indicative estimation and release planning. Your insight into complexity, risk and security accreditation timelines helps product owners sequence work so that mission-critical features land exactly when clients need them.
• • Champion clean-code culture: open pull-requests early, request reviews from domain experts, and provide constructive feedback that raises collective standards. Expect the same in return—our definition of done includes two approvals and passing static-analysis gates on SonarQube.
• • Mentor junior contractors and client secondees. A 30-minute explanation from you can save days of confusion for someone new to cross-domain constraints or UK OFFICIAL-SENSITIVE data handling rules.
• • Stay sharp with 10% self-directed learning time. Whether you choose to deep-dive into Project Loom, explore eBPF for container security, or study the latest NCSC patterns, the investment feeds directly back into the codebase and client trust.