orpc

oRPC solves a specific annoyance: your frontend calls your backend, and nothing tells you when the two quietly disagree about the shape of the data. Define the contract once and TypeScript flags the mismatch in your editor instead of in production. MIT licensed, no paid tier, no hosted service waiting to upsell you.

There is nothing to run. oRPC is npm packages you import into whatever stack you already have, with adapters for Next.js, NestJS, Bun, and Cloudflare Workers. Contract-first is the real differentiator: you write the API shape as a standalone artifact and get an OpenAPI spec out of it, so consumers that are not TypeScript are not locked out. tRPC gives you type safety without the spec; ts-rest gives you the contract without the adapter breadth.

Solo and small teams running TypeScript on both ends get the most out of this. Medium teams with a mixed stack still come out ahead because of the OpenAPI output. Large teams already deep in tRPC should leave it alone; the win is real but not migration-sized.

The catch is that this is still pre-1.0 with more than twenty packages in the monorepo. Breaking changes are landing, and "which packages do I actually need" is a real first-day question. Pin your versions.