Code modernisation with Claude accelerates the analysis, refactoring, and migration of legacy systems — from COBOL mainframes to Python microservices — at a pace no traditional approach can match. Our Claude Certified Architects run the programme; Claude does the heavy lifting.
Claude's 200K context window processes entire repositories in one pass. We build the workflow around that capability — so your engineers stop reading dead code and start shipping production-grade replacements.
We feed your entire codebase — COBOL, FORTRAN, VB6, legacy Java, anything — into Claude for complete dependency mapping, dead code identification, and architectural analysis. What takes a team six weeks takes Claude six hours.
Claude generates refactored equivalents with full test coverage suggestions, inline documentation, and compliance with your target language standards. Engineers review and approve — they don't write from scratch.
COBOL to Python. VB6 to C#. Legacy SQL stored procedures to modern ORM layers. We use Claude to translate business logic faithfully, with diff-based review gates so nothing gets lost in translation.
Claude maps service boundaries within monolithic systems, identifies data ownership, and generates decomposition blueprints. We use this to prioritise which services to extract first and in what sequence.
Undocumented legacy code is a risk every auditor flags. Claude reads the actual logic and generates accurate, human-readable API documentation, data dictionaries, and architecture decision records in hours.
Legacy systems often ship with zero test coverage. Claude generates unit tests, integration tests, and regression suites from the existing code, giving you a safety net before any migration begins.
Every engagement follows a structured programme. We don't hand you a tool and walk away — we run the migration with you, from first audit to last production deployment.
We run a codebase ingestion across your full repository footprint — regardless of language, size, or age. Claude produces a dependency graph, a risk inventory (cyclomatic complexity, dead code, hardcoded credentials), and a migration complexity score for every module. Typical turnaround: 2–5 business days for codebases up to 2 million lines. This replaces the months-long manual assessment phase that delays most code modernisation with Claude projects before they begin.
Using Claude's analysis, we produce a sequenced migration roadmap: which modules to tackle first, what target architecture looks like, where risk is concentrated, and what your engineering team needs to handle vs. what Claude automates. We present this as a prioritised backlog with effort estimates derived from Claude's complexity scoring — not gut instinct.
We run two-week migration sprints where Claude handles translation, refactoring, and test generation. Your engineers focus on architectural decisions, edge cases, and domain knowledge that no AI can replicate. Each sprint delivers a production-ready module, reviewed against your coding standards, with full audit trail. Our Claude Code Enterprise service integrates directly into these sprints for developer tooling.
Every migrated module runs in parallel with its legacy counterpart for a defined period. Claude generates the regression test suite. We instrument both paths and compare output parity. Nothing goes live until it passes your acceptance criteria — and we've defined those acceptance criteria together at the start of the engagement.
Once parity is confirmed, we execute the cutover with rollback procedures in place. We deliver comprehensive documentation generated by Claude, run knowledge-transfer workshops for your engineering team, and leave you with a Claude Code workflow your developers can use to maintain and extend the modernised system independently.
Code modernisation with Claude is most impactful when the problem is genuinely large and the risk of inaction is measurable.
You're running COBOL on z/OS because every attempt to move it has failed or stalled. The talent pool is shrinking and the auditors are asking harder questions every year. Claude changes the economics of migration completely — and we've run this in regulated environments before.
Your ERP customisations are undocumented. The developer who wrote them left in 2011. You're afraid to touch the system, so you build workarounds on top of workarounds. Claude can read it, document it, and give you a migration plan in days.
Government systems carry decades of accumulated complexity, compliance requirements, and zero appetite for downtime. Our code modernisation with Claude service is designed for high-stakes environments where the migration must be auditable, reversible, and defensible to procurement.
Every month you wait is another month your best engineers maintain systems they didn't write, in languages they never chose to learn. Book a free assessment call and we'll show you exactly what Claude finds in your codebase.
Claude handles virtually any language that has been in production: COBOL, FORTRAN, RPG, VB6, Classic ASP, Delphi, legacy Java (pre-JDK 8), PL/SQL, and more. The migration targets are typically Python, Java 21, C#, TypeScript, or Go — depending on your target architecture. We've also worked with IBM mainframe environments and VAX/VMS systems. If you have something unusual, bring it to the discovery call and we'll tell you directly what's achievable.
Claude Opus supports a 200,000-token context window — equivalent to roughly 150,000 lines of code in a single pass. For larger codebases, we use a chunked ingestion approach with persistent summaries, so Claude maintains architectural coherence across the full repository. We've processed codebases exceeding 5 million lines using this method.
Claude's output is reviewed, not shipped raw. Every module goes through a defined review gate: our architects check logic fidelity, your engineers validate domain correctness, and automated tests confirm output parity with the legacy system. Nothing goes to production without human sign-off. Our security and governance framework applies throughout.
Discovery and scoping takes 1–2 weeks. A focused module migration (say, a single 50,000-line subsystem) typically runs 6–10 weeks including parallel testing and cutover. Full platform modernisations for large enterprises run 6–18 months, depending on complexity and your team's capacity to absorb change. We don't pad timelines — we sequence the work to deliver production deployments every sprint.
Not necessarily. The code modernisation programme can run with our team using Claude Code — your engineers don't all need licences on day one. That said, the long-term value is highest when your engineers adopt Claude Code Enterprise as their daily development environment. We build that adoption plan into the final phase of every engagement.
Yes. We've run code modernisation with Claude in financial services, healthcare, and government environments. All work is conducted in your cloud environment or on-premises if required — code never leaves your perimeter. We follow our Claude security and governance framework throughout, and we can produce audit-ready documentation of every migration decision for compliance purposes.