03 · ModerniseRenascia, the upgrade and migration sprint
Move from legacy to modern technology, without a risky rewrite
Legacy application modernization (or modernisation, in British spelling) is not a rewrite. It is a sequence of small, reversible changes that move a working application onto supported frameworks, runtimes and hosting — with tests proving nothing broke and your search rankings kept. We do this for applications built on .NET Framework, AngularJS, and older versions of React, Next.js and Node.js, at a fixed price set by the Perlustra audit.
01Migrations
Migrations we take on
| Moving from | To | How |
|---|---|---|
| .NET Framework: ASP.NET MVC, Web API, WebForms, WCF | .NET 10, the current long-term-support release | Route by route behind a proxy; WebForms and WCF with explicit strategies. The .NET page. |
| AngularJS (Angular 1.x) | React or modern Angular | The strangler pattern: old and new run side by side and move route by route. The AngularJS page. |
| Older Next.js and React | Current major versions | Pages router to app router where it pays, React 18 to 19, codemods, breaking-change audits and a safe rollout. |
| End-of-life Node.js | A supported Node.js release | The dependency chains that block the upgrade, and the container images. |
| Windows/IIS or bare VMs | Linux containers or a managed platform | Only where it cuts cost or risk; moves between providers when the numbers say so. |
| Entity Framework 6, Sequelize, Mongoose | EF Core and current ORM versions | Query-by-query verification and tested migration tooling. |
02Method
How a migration sprint runs
Inventory
The audit produces the inventory: every framework, package and runtime with its end-of-life date and the blockers between here and there.
A plan in slices
A migration plan in slices, each shippable on its own, with a way back.
Tests first
Tests first around what the slice touches; then the change; then a demo on staging.
Cut over, slice by slice
Production cut-over per slice, behind feature flags or parallel routes where possible.
Handover
Documentation and a knowledge-transfer call at the end.
03Search
Your search rankings move with you
A migration that loses your search traffic is not finished. Every Renascia sprint includes the technical SEO work that keeps rankings in place:
- A redirect map. Every old address points to its new one with a permanent redirect, tested before launch.
- Rendering checks. Pages are checked the way search engines see them, so content and links are still there.
- Structured data kept. Titles, descriptions and schema markup are carried across and validated.
- Page speed before and after. Core Web Vitals measured on both sides of the move, with the numbers in the handover.
Engineering, not an SEO service
This is engineering work inside the sprint. We do not write content, build links or promise rankings.
04Small steps
Why small steps beat a rewrite
A rewrite freezes your roadmap for months, spends months of budget before it delivers anything, and reintroduces bugs the old system had already fixed. Incremental migration keeps the business running while the risk is removed piece by piece — and if you have to stop halfway, you still have a better application than you started with.
05AI-assisted
AI-assisted migration, honestly described
We use AI coding tools for code comprehension, mechanical code changes and test generation. They speed up the mechanical parts of this work: reading unfamiliar code, repetitive changes and first drafts of tests.
They do not replace judgement about what to migrate, in what order, or what to leave alone — which is why the price is fixed and the review is human.
06Questions
Frequently asked questions
Not answered here? Ask on the triage call.
What are the main risks of taking over a legacy codebase?
Unknown ownership of accounts, missing tests, undocumented behaviour that customers rely on, and hidden coupling. The audit surfaces all four before a price is set.
How long does a migration take?
Two to six weeks per sprint for an SMB application; larger estates run as a sequence of sprints with a pause point after each.
Can the application keep running during migration?
Yes. That is the point of the slice-by-slice approach; each slice has a way back.
Will we lose our search rankings?
Not if the migration is done properly. Every sprint includes a redirect map, rendering checks, structured data carried across and page speed measured before and after.
Do you migrate to the cloud at the same time?
Only if the audit shows it reduces cost or risk. Modernising the code and moving the hosting are separate decisions, and we say which one matters more in your case.
What do you need from us?
Repository and environment access, a person who can answer "what does this screen do?", and sign-off on each milestone.