Code modernization · Claude-assisted
We upgrade, migrate or rebuild ageing codebases with Claude doing the heavy reading and a Claude Certified Architect owning the plan. You get a sized, phase-by-phase modernization plan first, and every change after that lands as a reviewable pull request on your own repository.
Request a modernization assessment How it worksQuick facts. Three patterns (uplift, transform, reimagine) and seven phases (assess, map, extract rules, brief, build, verify, harden). Plans are sized in hours, not in a headline price, and a measured assessment of your own code replaces any first estimate. MSApps is Certified in the Claude Partner Network.
Most modernization projects go wrong at the first decision: treating a rebuild as a version bump, or the reverse. We borrow the vocabulary of Anthropic's open code-modernization plugin and choose one of three patterns per system.
Same stack, newer version. The code is preserved and tweaked: framework and runtime upgrades, dependency and security patching, deprecated API removal.
A different stack or platform. Behaviour is preserved while the code is re-expressed: cloud migration, end-of-life platforms, vendor or licence exits.
Rebuild from extracted business rules, when the code is not worth preserving: lost knowledge, languages with no practical upgrade path, rules nobody can state any more.
Inventory the code, dependencies, tests and hosting. Decide the pattern and what is out of scope.
Build a dependency and data-flow map so changes are planned against how the system really connects.
Write down the business rules the code actually implements, in plain language your team can confirm or correct.
A short, agreed modernization brief: target, boundaries, acceptance checks and phases.
Claude drafts the changes in small slices; engineers review each one as a pull request.
Characterization and regression tests prove behaviour matches, so "it compiles" is never the bar.
Security, observability and handover, so your team can run what we leave behind.
Modernization touches the most sensitive thing a company owns. Our working rules: access to your repository is least-privilege and starts read-only for assessment; nothing is merged without your reviewers; Claude's output is always checked by tests and a person; and every figure in a plan states its assumptions. Claude Self-Hosted deployments inside your own cloud perimeter are available when code must not leave it.
It is upgrading, migrating or rebuilding legacy software with Claude doing the large-scale reading, mapping and drafting, under the plan and review of an engineering lead. Work is split into assess, map, extract-rules, brief, build, verify and harden phases.
Uplift keeps the stack and moves versions. Transform moves to a different stack or platform while preserving behaviour. Reimagine rebuilds from extracted business rules when the existing code is not worth preserving.
For a measured assessment, yes, and we start with read-only access so nothing can be changed. Later phases deliver changes as pull requests that your own reviewers approve and merge.
It depends on code size, number of repositories, test coverage and the pattern chosen, so we do not publish a headline price. We size the work in hours per phase, state the assumptions, and replace the first estimate with a measured assessment of your code.
MSApps is Certified in the Claude Partner Network. Our modernization work is led by a Claude Certified Architect.
Yes. Claude can be deployed inside your cloud perimeter (Amazon Bedrock, Google Cloud Vertex AI or Microsoft Foundry) so prompts and source code stay in your environment.
Tell us the languages, frameworks, rough size and what hurts. We reply with the pattern we would pick and why.
Email michal@claudeservices.ai About our Claude practice