Off three stacks, without a freeze.
Moving a regulated reinsurance platform from .NET, Java and pre-framework JavaScript to TypeScript while the product kept shipping. Work led by our principal in regulated production before Aripone was formed.
- Client
- A regulated reinsurance company
- Team
- Our principal, Rey Narvaez, as lead engineer
- Outcome
- Releases from monthly to weekly
- Date
- 2024 to 2026
Same method as the modernization practice: make it recoverable, put one API in front, move one route at a time.
The problem
The platform ran on three stacks: ASP.NET pages on .NET Framework, Java services holding parts of the treaty and pricing logic, and front-end JavaScript written before any framework. Each needed a different engineer, and the company could not hire for two of them.
Releases went out once a month, by hand, because nobody could predict what a change in one stack would break in another. A full rewrite had been proposed and shelved, because the business could not stop shipping for the year it would take.
The fix
- Phase 0 made the move recoverable: one CI pipeline for all three stacks, infrastructure defined as code, and a restore of production data tested into a fresh environment.
- A versioned TypeScript API went in front of the .NET and Java services. Every screen and integration called it, and it sent each route to the old side or the new one.
- Before a calculation moved, its outputs were captured as tests. The same inputs ran through the old and the new code, and the route switched only after a comparison job matched.
- Screens moved to React one at a time, behind the same domain and sign-in, so users kept working the way they always had.
- Every switch had a rollback: one change to the API sent a route back to the old side.
- The mobile app was built in React Native on the same TypeScript services, so the business logic was written once.
| Part | From | To |
|---|---|---|
| Web screens | ASP.NET pages and pre-framework JavaScript | React and TypeScript |
| Treaty and pricing logic | Java services | TypeScript services behind the API |
| Mobile | None | React Native on the same services |
| Remaining endpoints | .NET Framework | Behind the API, each waiting for its gate |
The outcome
Releases went from monthly and manual to weekly, through the pipeline. The product shipped new features in every release during the migration, and there was never a freeze.
The Java services were retired once their last consumer moved. The team now works in one language across web, mobile and services, so the company hires for one stack instead of three.
Your platform
Find out what it takes to move yours.
The Modernization Assessment is two or three weeks at a fixed fee, published on the pricing page. We inventory every component and its consumers, test whether you can restore your data, and find the logic only one person understands. You get a disposition for each component, a target architecture, a risk register and a phased roadmap any team can execute.