AI-accelerated legacy modernisation
Modernise the systems you depend on without stopping the business
The systems that run the most important work are the hardest to change
Ageing systems often run core ledgers, billing, ERP extensions and back-office tools nobody wants to touch. They are hard to change, hard to staff and increasingly hard to secure, and the people who built them have often moved on.
Replacing them in one go is one of the riskiest projects a business can run. Vendor deadlines, such as the end of SAP ECC support, and resilience rules such as DORA add pressure to move.
What changes for you
No big-bang switch
Old and new run side by side, with their results compared, so the business keeps running at every step.
Modernisation at a faster pace
AI-assisted code analysis and refactoring, verified by engineers and tests, shortens the slowest part of the work: understanding the old code.
Licences and mainframes retired
Each replaced part is switched off, its data archived and its licences and infrastructure ended.
What we deliver
System and technical-debt assessment
An inventory of code, data, interfaces, dependencies and the people who know them, with the risks ranked.
Options and roadmap
For each part, a choice to keep, wrap, re-platform, rewrite or retire it, with the reasons and the order of work.
AI-assisted code refactoring
AI tools that read and explain old code, suggest refactorings and draft tests. Every change is reviewed by an engineer and checked by the test suite.
Strangler-fig migration
A modern API layer in front of the old system, with capabilities rebuilt behind it one at a time until nothing calls the old code.
Characterisation tests and parallel runs
Tests that record what the old system actually does, and old and new outputs compared on real workloads before each switch.
Database migration
Data mapped, cleaned and migrated from COBOL files, DB2 or Oracle Database to cloud-native databases, with reconciliation reports that show nothing was lost or changed.
Mainframe and monolith decommissioning
How each replaced part is switched off, its data archived for audit and its licences and infrastructure ended.
How we work
Understand the system
We read the code, trace the data and interview the people who run it, and record what it really does.
Choose the path
We decide with you which parts to keep, wrap, move or retire, and in what order.
Wrap
We put an API layer in front of the old system, so new work stops depending on its internals.
Replace piece by piece
We rebuild one capability at a time behind the API layer, with tests that show it matches.
Run in parallel
We run old and new side by side, compare their results and switch only when they agree.
Retire
We switch off what has been replaced, archive its data and remove its licences and infrastructure.
Technologies we modernise from and to
For rarer platforms we assess the code first and tell you plainly whether we have the skills. Naming a product does not mean a partnership with its vendor.
- Languages
- Java
- Frameworks
- .NET
- Databases
- Oracle Database
- Microsoft SQL Server
- PostgreSQL
- DevOps and observability
- Docker
- Kubernetes
- Integration
- SOAP
Zero disruption, backed by the contract
We do not ask you to trust a promise. Milestone acceptance gates, idempotent transactions with rollback and dead-letter queues, and a post-launch defect warranty are written into the agreement.
How to start
A live system that is failing or undocumented starts with the Brownfield Diagnostic Bridge. It is a short audit of the code, data and security. It ends in a candid verdict to rescue, refactor or rebuild, and a fixed-price proposal.
What happens next
Pre-consulting session
A free 30-minute online pre-consulting session: we go through your goals, systems and constraints.
Readiness review
In a free 48-hour readiness review, a Principal Architect checks your project against the 6-point Definition of Ready and recommends the track that fits.
Choosing the track
Scope-ready projects receive a binding proposal within 3–5 business days. Concept-stage projects start in the Blueprint Studio. A live system that is failing, undocumented or needs integration starts with a diagnostic of 1–2 weeks. The Blueprint Studio and the diagnostic each have a fixed fee, quoted in the proposal.
Delivery in five stages
Mobilisation, sprints with live demonstrations, integration and hardening, acceptance and go-live, then managed services. After launch comes a warranty period, then optional support and maintenance.
Fixed-outcome projects and round-the-clock managed services
Fixed-scope, milestone-driven delivery with named delivery leads, and round-the-clock application managed services under SLA governance.
Hybrid delivery and build-operate-transfer hubs
On-shore technical leadership with vetted nearshore and offshore capacity, complete build-operate-transfer capability centres and workforce localisation.
Questions and answers
Why not rewrite the whole system at once?
A full rewrite must match years of behaviour before it can replace anything, while the business keeps changing around it. Such projects often run long and launch with gaps. Replacing one capability at a time delivers value early and keeps the old system as a safety net. You can stop or change direction at any step.
Will the business have to stop during the migration?
The approach is designed so that it does not. The old system keeps running while each new part is built and proven in parallel. Work moves to the new part gradually and can move back if something is wrong. Where a data migration needs a switch-over, we rehearse it first and schedule it with you.
What does AI actually do in the modernisation?
It reads large amounts of old code quickly: explaining what a program does, tracing where data goes, suggesting refactorings and drafting tests. Engineers decide what changes, review every line and prove it with characterisation tests. AI speeds up understanding; it does not replace verification.
Nobody fully understands our old system. Can you still modernise it?
Yes, and that is common. We recover the knowledge from the code, the data, the logs and the people who use the system. We capture what it does in characterisation tests, which become the specification the new parts must meet.
Can you move COBOL and DB2 workloads off the mainframe?
Yes. We translate or rebuild COBOL programs as cloud-native services, and migrate DB2 data with reconciliation at every step. Batch jobs and file interfaces get modern equivalents. Parts that are stable and costly to move can stay behind an API layer until their turn comes.
When is it better to wrap a system than to replace it?
When the old core is stable and correct but hard to reach. Modern APIs in front of it let new channels, partners and products use its functions without touching its internals. We recommend replacement when the system blocks change, cannot be secured or can no longer be staffed.
A live system that is failing or undocumented?
The Brownfield Diagnostic Bridge audits the code, the data and the bottlenecks before anything is rescued or refactored.
What happens next
Readiness review
In a free 48-hour readiness review, a Principal Architect checks your project against the 6-point Definition of Ready and recommends the track that fits.
Brownfield diagnostic
In 1–2 weeks, our principal engineers audit your code, your ERP and database schemas, your APIs and your infrastructure, and scan for leaked secrets and weak cryptography.
Rescue, refactor or rebuild
You receive a candid engineering scorecard and a Rescue, Refactor or Rebuild verdict with a fixed-price remediation proposal.
Fee credited to the rescue
100% of the diagnostic fee is credited toward the rescue or integration when XSIS carries it out. The work then runs through the same five delivery stages.