--- title: Legacy Code Migration and Modernization with AI | Remqa url: https://remqa.com/code-migration updated: 2026-10-13 --- [Home](https://remqa.com/) / [Migrations](https://remqa.com/migrations) / Code migration Migrations # Legacy code migration, done in small, tested steps. Stuck on an old framework, an unsupported language version or a monolith nobody wants to touch? Remqa's engineers move it to a modern stack in stages, with AI doing the repetitive rewriting and engineers reviewing every change. [Book a free migration call](https://calendly.com/meghanaj-connect/30min)[See all migrations](https://remqa.com/migrations) In short Remqa migrates legacy applications to modern stacks: framework upgrades, language moves, monolith splits and platform moves. Engineers write characterization tests first, migrate in small shippable slices, use AI to draft repetitive changes and review every change before it merges. - The app keeps running throughout the migration - Each slice can be rolled back - Works in your repo, CI and code review process - Ends with docs, runbooks and a clean test suite Last updated October 13, 2026 ## The kinds of migrations we take on - **Framework upgrades:** AngularJS to Angular or React, old React class components to hooks, Django, Rails, Laravel and Spring version upgrades - **Language moves:** Python 2 to 3, JavaScript to TypeScript, old PHP or Java versions to supported ones - **Architecture changes:** pulling services out of a monolith, moving cron scripts into proper jobs, replacing a homegrown queue - **Platform moves:** on-prem or VM apps to containers and managed cloud services - **Script rescue:** the spreadsheet macros, cron jobs and one-off scripts the business quietly depends on ## How we do it 1 **Lock in current behaviour.** Before changing code, we write characterization tests around what the system does today, including the odd parts. 2 **Plan in slices.** The migration is split into small pieces that can ship on their own, so the app keeps running the whole time. 3 **AI drafts, engineers review.** Coding agents do the repetitive rewriting. An engineer reviews every change, and nothing merges without passing the tests. 4 **Ship behind flags.** New code runs alongside old code where possible, so each slice can be rolled back. 5 **Hand over.** Docs, runbooks and a clean test suite, so your team owns the result. ## Why not a big rewrite? Big-bang rewrites tend to run long, miss behaviour nobody wrote down and arrive all at once. A staged migration keeps the product working, shows progress every week and lets you stop at any point with a better codebase than you started with. More on the approach in [how AI-assisted legacy code migration actually works](https://remqa.com/blog/ai-legacy-code-migration). ## Who this is for Small teams that inherited an old codebase, companies whose framework has reached end of life, and AI startups who need engineering capacity for a migration without pulling their core team off the product. See also [FDE capacity on demand](https://remqa.com/forward-deployed-engineers). FAQ ## Common questions. **Q: Can AI really migrate a legacy codebase?** AI is good at the repetitive parts of a migration, such as rewriting patterns across hundreds of files. It still needs engineers to set up tests, plan the slices and review every change, which is how we run it. **Q: Will the app keep running during the migration?** Yes. We migrate in small slices behind tests and, where possible, feature flags, so the app keeps working and each step can be rolled back. **Q: Do you need access to our repository?** Yes. We work in your repo, your CI and your code review process, with the access your team grants. **Q: What languages and frameworks do you work with?** Most mainstream web and backend stacks, including JavaScript and TypeScript, Python, Java, PHP, Ruby, React, Angular, Django, Rails, Laravel and Spring. **Q: What do we get at the end?** A migrated codebase with a test suite, documentation and runbooks, so your team can own and extend it. Talk to an engineer ## Tell us what you are moving. In 30 minutes we look at your current system, where you want to go and what could go wrong. You leave with a plan, whether or not you work with us. [Book a free migration call](https://calendly.com/meghanaj-connect/30min) **30 minutes**Free, with an engineer **Your stack**We look at what you run today **Straight answer**Including when we're not the fit