Java Development in the UK

About Java Development

We build Java backends, Spring Boot REST APIs, and enterprise integrations for teams that run on the JVM. This is a newer service line for us, so here is the honest version: our highest-volume work is in Node.js and PHP, and what carries straight into Java is the part that decides whether a backend lasts, clean API design, a real test suite, CI on every push, and the PostgreSQL, Redis, and AWS work we already do every week. You work directly with the senior engineers writing the code, on a written scope and a flat quote.

What the engagement includes

• Spring Boot as the base, with a layered structure of controllers, services, and repositories that a new developer can navigate, not a tangle only the author understands.
• REST APIs documented with OpenAPI and Swagger UI, so your front-end and mobile teams build against a contract instead of a moving target.
• A real test suite: JUnit 5 and Mockito for units, Testcontainers and Spring Boot Test for integration tests that hit an actual PostgreSQL, so regressions get caught before your users do.
• CI that runs the build and the full test suite on every push, with Maven or Gradle, so the main branch stays in a shippable state.
• Database changes kept as versioned migrations in Flyway or Liquibase, never hand-edited straight into production.
• Containerized with Docker and deployed to AWS, with configuration and secrets kept out of the code.
• You own the repository, the pipeline, and the infrastructure from day one. Nothing is locked to us, and any competent Java team can pick it up.

UK Core FHIR, DCB0129 clinical safety and APP fraud reimbursement in a UK Java service

For a UK health integration the profiles to validate against are UK Core, published as NPM packages on the Simplifier registry, where fhir.r4.ukcore.stu2 stands at 2.0.2 with an stu3 current build beside it. Choosing between them is a decision for the first week, not a default: the chosen version is pinned in the Maven or Gradle build, and the test suite runs every resource the service produces through HAPI's validator against it, which catches what base FHIR R4 lets through and an NHS endpoint would refuse. The patient identifier is where a build written for another market first goes wrong. The NHS Data Dictionary defines the NHS Number as ten digits with a mandatory Modulus 11 check: the first nine digits are weighted from 10 down to 2 and summed, the remainder after dividing by 11 is taken from 11 to give the check digit, a result of 11 becomes 0, and a result of 10 means the number is invalid. That is a few lines of Java that run before any call to a national service, so a mistyped number fails on the form rather than in a lookup. Verification status is the next layer. UK Core carries it as an extension backed by two code systems, one for England and one for Wales, and they are not the same list: Wales adds a code for a number traced against its own NHS Administrative Register, and both include a status for a trace postponed because the baby is under six weeks old. A service that collapses those into a boolean called verified throws away information a clinician may need. So the domain model keeps the identifier system, the value and the coded status together, and the mapping layer is tested against the example resources shipped in the package. Which national APIs you may call, and on what onboarding terms, is for NHS England's assurance process to confirm.

In England a health IT system also needs a named clinician standing behind it. DCB0129, the clinical risk management standard for manufacturers of health IT, is published under section 250 of the Health and Social Care Act 2012, and its companion DCB0160 applies to the organisations that deploy and use the system. Under DCB0129 the manufacturer must have a Clinical Safety Officer who is a suitably qualified and experienced clinician holding current registration with an appropriate professional body. It must keep a hazard log that the Clinical Safety Officer approves at each version, produce a clinical safety case report at each lifecycle phase in its clinical risk management plan and make it available to the receiving organisation, and maintain a safety incident management log. After deployment, any change that alters clinical risk needs a fresh safety case report, and an audit trail of every version and patch released is kept. We do not supply the clinician; that role sits with you or with a Clinical Safety Officer you contract, and our part is making the evidence cheap to produce. NHS England's implementation guidance for middleware is blunt about integration work: a message that is incorrect, absent, corrupt or sent to the wrong destination can delay care, and the controls it names are validation of inbound and outbound messages against agreed criteria and reliable messaging that tells the source whether delivery succeeded or failed. In a Java integration service those become concrete choices: profile validation at both edges, idempotent consumers with dead letter queues that someone is assigned to watch, and acknowledgement handling that cannot be switched off quietly in configuration. With every deployable artefact versioned and traceable to its commits, the required audit trail already exists, and a pull request touching clinical logic is flagged for the Clinical Safety Officer before it merges. NHS England has begun reviewing both standards, so current versions are checked at the start of each project. Whether a component is in scope is for your Clinical Safety Officer to decide.

Payment firms in the UK carry a reimbursement duty that reaches into their Java back ends. Since 7 October 2024 the Payment Systems Regulator's requirement has covered authorised push payment fraud on Faster Payments and CHAPS between UK accounts. A victim should claim within 13 months of the payment, most are reimbursed within five business days, a firm that needs more information can stop the clock but must reach an outcome within 35 business days, the maximum claim is £85,000, an optional excess of up to £100 cannot be applied to vulnerable customers, and neither can the gross negligence exception. The cost is split 50:50 between the sending and receiving firms. Each of those is a rule in code. A claim is a case with a state machine and two clocks, one for the 13 month window and one in business days, and UK business days do not come from one calendar. The government's bank holiday feed publishes three divisions, England and Wales, Scotland, and Northern Ireland, and they differ: Scotland has 2 January and St Andrew's Day and takes its summer bank holiday on the first Monday of August, Northern Ireland adds St Patrick's Day and the Battle of the Boyne, and in 2026 Scotland also had a one-off World Cup bank holiday on 15 June. A java.time calculation built on a hard-coded holiday list breaks the first time that happens, so the calendar is loaded from the feed and the version used for each decision is stored with the case. The 50:50 split makes the receiving side matter as much as the sending side, so monitoring inbound payments for mule accounts belongs in the same service boundary as outbound fraud scoring. The vulnerability flag that removes the excess and the gross negligence exception is a field with an audit history, not a free-text note. Which calendar your reimbursement clock should follow is for your compliance team.

How we work with UK clients

UK engagements tend to start with procurement questions rather than technical ones. Who holds the data, which law governs the contract, whether you can produce a record of processing if the ICO asks. We answer those in the proposal instead of leaving them to a legal review three weeks in, because that review is where UK projects usually stall.

Invoicing is the other thing worth settling early. We are outside the UK, so services we supply generally fall under the reverse charge and your finance team accounts for the VAT rather than paying it to us. Our invoices say so explicitly. We quote in pounds, the figure does not move with the exchange rate mid-project, and payment by bank transfer avoids the card fees that make a five-figure invoice unnecessarily expensive.

Questions UK clients ask

Java Development: common questions

Other markets we work in