TypeScript vs JavaScript in Boilerplates

TL;DR In 2026, the question isn't whether to use TypeScript — it's how strictly. 98%+ of SaaS boilerplates ship TypeScript by default. The benefits are real: fewer runtime bugs, better DX, and type-safe API layers. The downside: TypeScript adds setup friction and any -heavy code is worse than JavaScript. The Current State A sample of popular boilerplates: Boilerplate Language TypeScript Strictness T3 Stack TypeScript Strict ( strict: true ) ShipFast TypeScript Moderate Supastarter TypeScript Strict Makerkit TypeScript Strict Epic Stack TypeScript Strict Open SaaS TypeScript Moderate JavaScript-only boilerplates in 2026: nearly zero in the mainstream. Why TypeScript Won 1. Type-Safe API Layers (tRPC Changed Everything) tRPC gives you end-to-end type safety between server and client — but only with TypeScript: // Server: define your API once const postRouter = createTRPCRouter ({ getById : publicProcedure . input ( z . object ({ id : z . string () })) . query ( async ({ input }) => { ret