oRPC BackendEnd-to-end type-safe RPC with OpenAPI support
oRPC combines the DX of tRPC with OpenAPI spec generation — define your procedures once and get type-safe client calls and an auto-generated OpenAPI schema. Best of both worlds for APIs consumed by both internal clients and external partners.
oRPC combines the developer experience of tRPC with OpenAPI specification generation — define your procedures once and get type-safe client calls for internal consumers and a standards-compliant OpenAPI schema for external partners. At A Major, we recommend oRPC for teams that want tRPC-style DX but also need to expose documented REST APIs. oRPC supports Zod and Valibot for validation, generates OpenAPI 3.1 schemas automatically, and integrates with Next.js, Hono, and Fastify. Its React Query client provides typed query and mutation hooks — the same ergonomics as tRPC with broader interoperability.
Quick start
npm init -y
npm install @orpc/server @orpc/client zod
npx tsx src/server.tsRead the full documentation at orpc.unnoq.com
Type-safe from day one
Input and output types inferred from your procedure definitions — TypeScript errors if you break the contract.
OpenAPI spec generation
Automatic OpenAPI 3.1 schema from your router — Swagger UI and partner integrations without extra work.
Zod / Valibot validation
Bring your own validation library — oRPC handles the plumbing, you write the schema.
Middleware pipeline
Composable middleware for auth, rate limiting, tracing, and error formatting.
Framework adapters
Next.js, Hono, Fastify, and Node.js HTTP — plug oRPC into your existing server.
React Query client
First-class TanStack Query integration — oRPC procedures become typed query/mutation hooks.
Why it's hard
Early-stage ecosystem
oRPC is newer than tRPC with a smaller community. Expect fewer third-party plugins, tutorials, and Stack Overflow answers.
Migration from tRPC
While conceptually similar, migrating from tRPC to oRPC requires rewriting router definitions and updating client code.
OpenAPI schema complexity
Auto-generated OpenAPI schemas can become large and require manual refinement for clean public documentation.
Best practices
Use Zod for input/output schemas
Zod schemas provide runtime validation, TypeScript types, and feed directly into OpenAPI generation — one schema does triple duty.
Organize procedures by domain
Group related procedures into routers by domain feature — keeps the API surface navigable as it grows.
Generate typed clients for external consumers
Use the auto-generated OpenAPI spec to produce typed SDKs in TypeScript, Python, and Go for external partners.
Use middleware for cross-cutting concerns
Auth, rate limiting, and logging belong in oRPC middleware — not duplicated across individual procedures.
Useful resources
Frequently asked questions
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