TypeScript Development Services
Type-safe web development — from greenfield builds to migrating an existing JavaScript codebase
Why TypeScript earns its place
TypeScript doesn't make a project faster to start. It makes a project cheaper to change six months later, when the person editing the code isn't the person who wrote it. The type system forces the shape of data to be explicit, so the editor catches the wrong call before the test suite does, and the test suite catches it before the user does.
Whoooop Ltd writes TypeScript across all our production work — React front-ends,
Next.js applications, and
Node.js back-end services. We run in strict mode, which means
the compiler flags implicit any, unguarded nullable access, and the other corners a
lenient configuration lets you ignore until something breaks in production.
TypeScript development services
New TypeScript applications
Greenfield builds structured around TypeScript from the first commit — strict mode on, types defined before the data flows that use them, no any escapes left as tech debt. The project starts with a clear type model rather than retrofitting one later.
JavaScript to TypeScript migration
Incremental migration of an existing JavaScript codebase. We rename files, add initial types, configure tsconfig, and tighten the types over time — keeping the project shippable throughout rather than rewriting it in a branch that can't merge for three months.
Type system design
Modelling a complex domain accurately: union types and discriminated unions for things with multiple states, generics for code that works across several shapes of data, branded types when a plain string or number needs to mean something specific. Types that reflect the problem rather than just satisfying the compiler.
TypeScript with React
Typed component props, properly typed hooks, event handler types that match what the DOM actually sends. A React codebase in TypeScript catches a whole class of mistake — wrong prop name, wrong event type, missing required field — at the point where you type it, not at the point where the user sees it.
TypeScript on the back end
Shared types between a Node.js API and a React front-end mean the data contract is checked at both ends. If the API response changes shape, the compiler tells the front end immediately — before anything is deployed. There's more on the back-end side on our web application development page.
TypeScript codebase audit
Taking on an existing TypeScript project that has accumulated loose any types, disabled checks, or types that don't actually match the data? We read through, document the gaps, and work through them in priority order — tightening the configuration and paying down the type debt without breaking what already works.
When TypeScript makes sense
TypeScript adds overhead: a build step, a configuration file, a discipline around type definitions. For a short-lived script, a quick proof of concept, or a project you'll throw away in a week, that overhead is probably not worth it. For anything you'll maintain, hand to another developer, or build a second system that talks to — it usually is.
The tipping point tends to be team size and time. A solo developer working on a project they wrote alone can hold the shape of everything in their head. Add another developer, or add six months, and that context is gone. TypeScript puts it in the codebase where it can't be forgotten.
How we work with TypeScript
- Strict mode on by default —
strictNullChecks,noImplicitAny, and the rest - Types that model the domain, not just satisfy the compiler
- Shared type definitions between front end and back end wherever the project allows it
- Runtime validation (Zod, Valibot, or similar) at API and form boundaries, where TypeScript's static guarantees stop
- 15+ years of full-stack experience behind the type decisions, so they reflect how the data actually moves through a system
Working with TypeScript?
Whether you're starting from scratch or trying to tame an existing JavaScript codebase, tell us what the project looks like.
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