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Think of effect-orpc as a thin Effect-aware layer around oRPC. It does not replace oRPC. It lets you keep oRPC’s routing, validation, contracts, middleware, and client surface while using Effect for implementation logic.

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Core pieces

PieceRole
eosDefault Effect-aware oRPC builder.
.provide(layer)Provides base Effect services to downstream middleware and handlers.
.provide(tag, provider)Builds a request-scoped service from oRPC context and input.
.effect(handler)Defines a procedure handler as an Effect generator.
ORPCTaggedErrorDefines yieldable Effect errors that map to oRPC errors.
makeEffectORPC(runtime)Uses a caller-owned ManagedRuntime instead of acquiring a layer per call.

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Builder-first flow

Most applications start by creating a reusable procedure builder:
procedure.ts
import { eos } from "effect-orpc";

export const publicProcedure = eos.provide(AppLive);
Then each route adds input, output, errors, route metadata, middleware, and finally a handler:
users.ts
export const getUser = publicProcedure
  .input(GetUserInput)
  .output(User)
  .errors({ UserNotFoundError })
  .effect(function* ({ input }) {
    const user = yield* UsersRepo.findById(input.id);
    if (!user) return yield* new UserNotFoundError({ data: { id: input.id } });
    return user;
  });

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Runtime boundaries

Effect-native steps are batched into one runtime boundary, so Effect.runPromiseExit is ran only once if possible.
one-boundary.ts
eos
  .provide(AppLive)
  .provide(CurrentUser, ({ context }) => Effect.succeed(context.user))
  .use(function* ({ next }) {
    const user = yield* CurrentUser;
    return yield* next({ context: { userId: user.id } });
  })
  .effect(function* ({ context }) {
    const user = yield* CurrentUser;
    return `${context.userId}:${user.id}`;
  });
Native oRPC middleware can split the Effect pipeline. If you need fiber context to cross those split boundaries in Node, use the Node bridge guide.

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Default path vs guides

  • The default path is framework-free: eos, .provide(...), .effect(...), and tagged errors.
  • Guides cover integrations and non-default runtime concerns such as Hono, OpenTelemetry, the Node fiber context bridge, and testing.

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Next step

Continue to Effect procedures.
Last modified on June 15, 2026