ShouldYourStartupMigratetoTypeScript?APracticalGuide

TypeScript catches a real category of bugs at write-time (mismatched data shapes, incorrect function arguments) that would otherwise only surface at runtime, sometimes in front of a real user. It also makes a codebase more self-documenting — a function's types describe what it expects and returns, which matters increasingly as more people (or more time) touches the same code.

This value compounds with codebase size and team size — the bigger and longer-lived the project, and the more people working in it, the more a type system pays for itself by catching integration mistakes early rather than in production.

For a small, single-developer, rapidly-changing MVP, full TypeScript migration is often not the highest-value use of limited engineering time — the codebase is small enough that a developer can hold its shape mentally, and requirements are shifting fast enough that type definitions may need frequent rewriting anyway. As the codebase and team grow, and requirements stabilize into a longer-term product, the case for TypeScript strengthens significantly.

New projects are a different question — starting in TypeScript from day one avoids a migration cost entirely and is a common, low-risk default for most new products beyond the very smallest prototype, since the added type-safety benefit accrues from the start rather than needing to be retrofitted later.

If you decide to migrate an existing codebase, an incremental approach — TypeScript supports JavaScript and TypeScript files coexisting in the same project — lets you convert file by file rather than requiring a disruptive, all-at-once rewrite. This spreads the migration cost over time and avoids pausing feature development to complete it.