RPC, gRPC & OpenAPI

gRPC

grpc/grpc

Popular

High-performance RPC framework over HTTP/2 with Protocol Buffers; the standard for service-to-service calls.

Protocol Buffers

protocolbuffers/protobuf

Popular

Google's language-neutral binary serialization format and IDL behind gRPC.

Buf

bufbuild/buf

Modern Protobuf toolchain for linting, breaking-change detection, code generation and a schema registry.

tRPC

trpc/trpc

End-to-end type-safe APIs for TypeScript monorepos without schemas or code generation.

Connect RPC

connectrpc/connect-go

Trending (detected automatically)

CNCF Protobuf RPC protocol and libraries that speak gRPC, gRPC-Web and plain HTTP from browsers and servers.

oRPC

middleapi/orpc

Trending (detected automatically)Rising

Type-safe RPC in the spirit of tRPC with first-class OpenAPI output and contract-first support.

OpenAPI Specification

OAI/OpenAPI-Specification

Popular

Vendor-neutral standard for describing HTTP APIs that drives docs, mocks, SDK and server generation.

Swagger UI

swagger-api/swagger-ui

Popular

Ubiquitous interactive API documentation generated from OpenAPI definitions.

Scalar

scalar/scalar

Trending (detected automatically)Rising

Modern open-source API reference and client for OpenAPI, increasingly replacing Swagger UI.

OpenAPI Generator

OpenAPITools/openapi-generator

Generates clients, server stubs and docs in 50+ languages from OpenAPI specs.

Hey API

hey-api/hey-api

Rising

OpenAPI code generator producing typed SDKs, Zod schemas and TanStack Query hooks.

TypeSpec

microsoft/typespec

Rising

Microsoft's API description language that compiles to OpenAPI, JSON Schema and Protobuf.

protobuf.js

protobufjs/protobuf.js

High-performance Protocol Buffers for JavaScript and TypeScript. Conformant through Edition 2026, and unusually versatile. No protoc…

ReDoc

Redocly/redoc

OpenAPI/Swagger-generated API Reference Documentation