Spring Boot services
Spring Boot 3+, reactive (WebFlux) where the workload demands it, virtual threads (Project Loom) for high-concurrency I/O.
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Senior engineering · Java
Senior Java engineering for production systems.
Java engineering for enterprise scale — Spring Boot, Micronaut, Quarkus, JVM tuning, and the legacy modernization work that doesn't end in a six-month rebuild.
- In production
- 2018+
- Senior bench
- 35+ G6/G9 engineers
- Floor
- G6+ on client work
- Engagement
- Outcome-led, not hourly
Why senior, not contractor
Java in production is a different problem than Java on a laptop.
Java is the substrate of the enterprise — and most enterprise Java is stuck on stacks that EOLed two LTS cycles ago. Prosigns runs Java engagements as production engineering: modern Spring Boot with reactive patterns where they fit, Micronaut / Quarkus for serverless and AOT-compiled workloads, JVM tuning that the operations team can defend, and modernization off legacy Java EE / Spring 3 with strangler-fig discipline rather than big-bang rebuilds.
Senior floor
G6+ minimum
Bench depth
35+ G6/G9 engineers
In production
2018+
Engagement
Outcome-led SOW
Where Java ships
6 sub-areas, grounded in shipped engagements.
Specific applications of Java we’ve built and operate. Every example below maps to a real engagement, not a bullet on a stack-card.
01 02 Micronaut + Quarkus AOT
Native-image compilation for fast cold starts on serverless / Kubernetes. GraalVM tuning for production deployment.
03 JVM tuning + GC discipline
ZGC / Shenandoah / G1 selection for the workload, heap profiling, allocation analysis, latency budgets defended.
04 Event-driven on the JVM
Kafka Streams, Flink, Akka, Spring Cloud Stream. Exactly-once where the workload requires it; clear failure semantics elsewhere.
05 Legacy modernization
Java EE / WebSphere / WebLogic / Spring 3 → modern Spring Boot with phased cutover, parallel-run, and reconciliation harnesses.
06 Java → Kotlin migrations
Phased Kotlin adoption for new modules with Java interop discipline. Gradle build modernization, KSP migration from KAPT.
Stack depth
The Java ecosystem, owned.
Frameworks, libraries, and runtime tools the bench has shipped in production. Not a CV-skim — a working depth.
Frameworks
- Spring Boot 3
- Micronaut
- Quarkus
- Helidon
- Vert.x
Reactive + concurrency
- WebFlux
- Project Reactor
- Virtual Threads
- RxJava
- Akka
Data + persistence
- JPA / Hibernate
- jOOQ
- Spring Data
- R2DBC
- MyBatis
Build + tooling
- Gradle
- Maven
- GraalVM
- JIB
- JReleaser
Quality + ops
- JUnit 5
- Testcontainers
- OpenTelemetry
- Micrometer
- ArchUnit
Engagement models
Three ways to engage Java engineers.
We don’t bill hourly contractors. Engagements run against outcomes — choose the shape that matches the work.
See engagement models- 01
Fixed-scope
Defined deliverable, fixed price
When the deliverable is clear and the scope is bounded — an MVP, a migration, a discrete platform build. Senior engineering against a written outcome, not against a body count.
- 02
Embedded squad
Senior product team, ongoing
When the work is product-shaped and the cadence is continuous. A senior pod (engineering + design + PM as needed) embedded into your team, with the practice lead co-piloting from HELM.
- 03
Managed services
Steady-state operations
When the system is running and needs ongoing engineering ownership — operations, SLO defense, release management, security and compliance evidence. Monthly retainer against a published SLA.
Selected work
Java engineering that shipped.
Financial services
Strangler-fig modernization of a 19-year-old Java monolith for a regional bank.
0production incidents at cutover143 bounded contexts catalogued; 47 migrated to Spring Boot 3, 31 retired, 65 retained. Phased cutover over 14 months with feature flags and reconciliation harnesses.
Duration · 14 months
Brief us
Reply < 4 business hoursHave a Java workload? Send a brief.
Five fields. Goes straight to the practice lead — not an SDR. We’ll reply with a senior engineer’s read on fit, scope, and the engagement model that suits the work.
FAQ
Questions buyers ask.
Everything below also appears in the proposal and the SOW — no surprises after signing.
Java or Kotlin for new services?
Kotlin if the team can absorb it — better null safety, cleaner syntax, full Java interop. Java for shops where the team or vendor ecosystem demands it, or where Kotlin's roadmap risk is considered too high. Both are first-class on the JVM and we ship both.
Reactive or imperative Spring?
Imperative + virtual threads (Project Loom on JDK 21+) is the new default for most workloads — gets you reactive's I/O scalability without the cognitive overhead. Reactive (WebFlux) only when backpressure or streaming is the actual model. We'll tell you which fits.
Is this staff-aug, or is it engineering-led delivery?
Engineering-led delivery. We don't bill hourly contractors against your JIRA board. Every engagement runs against a defined outcome with a senior engineer accountable from kickoff to operating cutover. If you genuinely need staff-aug — discrete bodies, your management, hourly rates — we'll be honest and route you to a partner that fits.
What seniority floor are we talking about?
G6 minimum (six-plus years in their craft) on every billable hour. Department leads are G9 or G10. We don't flex juniors onto the bench mid-sprint, we don't subcontract to delivery centers, and we don't dilute senior rates with mixed staffing. The bench in the proposal is the bench in production.
How does pricing work?
Three engagement models published at /engagement-models/. Fixed-scope for defined deliverables, embedded squads for ongoing product work, managed services for steady-state operations. Rates depend on seniority, engagement length, and region. Discovery + scoping conversation is free; SOWs are written against deliverables, not bodies.
Where are your engineers based?
Senior-only across Dallas, Doha, Lahore, and Islamabad. We staff against the engagement's needs (timezone, language, regulatory frame), not against arbitrary regional preferences. Most engagements run with a US/EU-aligned core and a follow-the-sun extended bench when the workload warrants it.
Will the engineers I see in the proposal be the engineers shipping the work?
Yes. We name the engineers in the SOW, attach their profiles, and they're on the kickoff. We don't bait-and-switch with senior reviewers and junior execution. If a named engineer needs to roll off the engagement (rare), we surface a replacement from the same seniority tier with explicit handoff.
Talk to a Java lead
Senior Java engineering, accountable from kickoff.
Bring the workload — we’ll bring a senior engineer plus the practice lead most relevant to the work. 30 minutes, no obligation, no junior reps.