TypeScript

Usually, and rarely as a rewrite. The compiler accepts JavaScript and TypeScript side by side, so migration proceeds file by file while the product keeps shipping. We start at the boundaries: API contracts and shared data shapes are typed first, because that is where breakage crosses between modules and teams undetected.

The cost is front-loaded, build tooling, a period of mixed idioms, a backlog of loose types to tighten, and it repays fastest on codebases with years left in them. On code that is due for retirement the migration is rarely worth starting.

Yes where the back end is Node.js, because that is where end-to-end inference becomes available: a tRPC router or shared Zod schemas make the server's types the client's types, and an API change becomes a compile error in the front end that consumes it. That property does not survive a language boundary, so a Java or C# back end keeps its own type system and the contract moves through OpenAPI instead.

The decision is rarely TypeScript against another language on merit alone. A capable Java or .NET estate already serving the product is not worth replatforming for shared types; a back end being built new beside a React front end makes the single-language case strong. The Node.js page covers the runtime side of that choice.

Of the stacks we deliver in, TypeScript makes the strongest case, and the mechanism is the compiler. A coding agent improves with the speed and quality of its feedback, and tsc returns a machine-checkable verdict on every edit in seconds, long before a test suite runs. The training corpus is deep as well, since public TypeScript and JavaScript code overlap almost completely.

The signal is only as strong as the configuration: a strict compiler setup catches whole classes of plausible but wrong generated code that loose settings let through. With strictness and a fast test suite in place, the loop tightens to generate, check and correct within seconds. The measured results of our AI-augmented delivery flow are on the Technology page.

Largely the same things that make it easy or hard for engineers. Explicit types at module boundaries, few any escape hatches and a fast test suite give an agent a tight loop to verify its work in; a codebase where any spreads gives the compiler, and therefore the agent, little to check against. Heavy type-level programming cuts both ways: it encodes more correctness, and it is also where generated changes still need close line-by-line review, because intricate conditional types are rare in the public corpus and agents mishandle them.

TypeScript overlaps nearly the whole of our web engineering pool, since it is the working language of both our React and Node.js teams, so a shortlist usually reaches you within 48 hours of a brief. It draws on people we already employ or already know, with dedicated recruitment covering the rest.

Engagements start at one engineer, on terms of three, six, nine or twelve months chosen up front.

Yes. Plenty of sound production codebases are plain JavaScript, and our engineers work in them as they stand.

Where a codebase is expected to live for years, we will usually suggest turning the compiler on without renaming a file: allowJs and checkJs bring TypeScript's checking to JavaScript through JSDoc annotations, so the signal arrives before any migration is committed to. Whether to go further is your decision, and the staffing does not depend on it.