Connect-RPC

Connect is a slim framework for building browser-friendly and gRPC-compatible HTTP APIs from Protocol Buffer schemas. Servers built with Connect speak the Connect protocol, gRPC, and gRPC-Web simultaneously, while clients can switch between protocols without changing code. Connect provides type-safe SDKs for Go, TypeScript/JavaScript, Swift, Kotlin, and Python, plus the Buf-generated `protoc-gen-connect-*` code generators. The project is open source under the Apache 2.0 license and is maintained by Buf.

Connect-RPC publishes 5 APIs on the APIs.io network. Tagged areas include Apache 2.0, Buf, Code Generation, Connect Protocol, and gRPC.

Connect-RPC’s developer surface includes documentation, engineering blog, and 8 more developer resources.

🌐 Visit website 📡 Source on GitHub

15.0/100 emerging ▬ flat Agent 3/100 human only Front door AI 1/6 silent Full breakdown ↓
scored 2026-09-25 · rubric v0.23.0

AccessFreemium

5 APIs

Apache 2.0BufCode GenerationConnect ProtocolgRPCgRPC-WebHTTP Open Source Protocol Buffers RPC SDK

Kin Score

Kin Score How this is scored →
scored 2026-09-25 · rubric v0.23.0

Composite quality — 15.0/100 · emerging

Contract Quality 0.0 / 21

Developer Ergonomics 4.9 / 17

Access Clarity 2.7 / 17

Operational Transparency 1.2 / 11

Contract Governance 0.0 / 10

Discoverability 5.3 / 9

Regulatory Posture 0.9 / 15

Agent readiness — 3/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/connect-rpc: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 5

Individual APIs this provider publishes, each with its own machine-readable definition.

connect-go

The Go implementation of Connect. Provides server handlers and clients that speak the Connect, gRPC, and gRPC-Web protocols simultaneously. Generated from .proto files via the p...

connect-es (Connect for ECMAScript)

Connect for ECMAScript provides type-safe browser and Node.js clients and Node.js servers from Protobuf schemas. Targets the Connect protocol and gRPC-Web with idiomatic TypeScr...

connect-swift

Connect for Swift provides type-safe Connect, gRPC, and gRPC-Web clients for iOS, macOS, watchOS, and tvOS apps, generated from Protobuf schemas via protoc-gen-connect-swift.

connect-kotlin

Connect for Kotlin provides type-safe clients for Android and JVM applications. Speaks the Connect protocol, gRPC, and gRPC-Web from a single SDK generated by protoc-gen-connect...

connect-python

Connect for Python (beta) provides Connect protocol and gRPC clients generated from Protobuf schemas. Targets ASGI servers and async Python with type-safe stubs.

Pricing Plans 1

Published pricing tiers and plan structures.

Connect Rpc Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Connect Rpc Rate Limits

5 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Connect Rpc Finops

FINOPS

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Connect Rpc Domain Security

TLSv1.3 · HSTS

SECURITY

Resources

Get Started 1

Portal, sign-up, and the first successful call

Demo

Demo

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Slack

Slack

Commercial 1

Pricing, plans, and the legal terms of use

License

License

Company 3

The organization behind the API

Website

Website

Blog

Blog

BlogRSS

BlogRSS

Other 1

Properties that don't map to a standard resource type

Maintainer

Maintainer

Source (apis.yml)

aid: connect-rpc
name: Connect-RPC
description: Connect is a slim framework for building browser-friendly and gRPC-compatible HTTP APIs from Protocol Buffer
  schemas. Servers built with Connect speak the Connect protocol, gRPC, and gRPC-Web simultaneously, while clients can switch
  between protocols without changing code. Connect provides type-safe SDKs for Go, TypeScript/JavaScript, Swift, Kotlin, and
  Python, plus the Buf-generated `protoc-gen-connect-*` code generators. The project is open source under the Apache 2.0 license
  and is maintained by Buf.
type: Index
deliveryModel:
  model: unknown
  license_evidence:
    not_product:
    - connectrpc/connect-es
    - connectrpc/connect-go
    - connectrpc/connect-kotlin
    - connectrpc/connect-python
    - connectrpc/connect-swift
  open_source: unknown
  commercial: false
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - repository-not-product
  generated: '2026-09-25'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
position: Producing
access: Open Source
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/connect-rpc.png
url: https://raw.githubusercontent.com/api-evangelist/connect-rpc/refs/heads/main/apis.yml
created: '2026-03-25'
modified: '2026-04-28'
specificationVersion: '0.23'
kind: opensource
tags:
- Apache 2.0
- Buf
- Code Generation
- Connect Protocol
- gRPC
- gRPC-Web
- HTTP
- Open Source
- Protocol Buffers
- RPC
- SDK
tags_raw:
- Apache 2.0
- Buf
- Code Generation
- Connect Protocol
- gRPC
- gRPC-Web
- HTTP
- Open Source
- Protocol Buffers
- RPC
- SDKs
- Open-Source
apis:
- aid: connect-rpc:connect-go
  name: connect-go
  description: The Go implementation of Connect. Provides server handlers and clients that speak the Connect, gRPC, and gRPC-Web
    protocols simultaneously. Generated from .proto files via the protoc-gen-connect-go plugin and designed to slot into idiomatic
    net/http servers.
  humanURL: https://connectrpc.com/docs/go/
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  tags:
  - Go
  - SDK
  properties:
  - type: Documentation
    url: https://connectrpc.com/docs/go/
  - type: GettingStarted
    url: https://connectrpc.com/docs/go/getting-started
  - type: GitHub
    url: https://github.com/connectrpc/connect-go
  - type: Tutorial
    url: https://connectrpc.com/docs/go/tutorial
  x-features:
  - Connect Protocol Server and Client
  - gRPC Compatibility
  - gRPC-Web Compatibility
  - Streaming RPCs
  - Interceptors
  - Idiomatic net/http Integration
  x-use-cases:
  - Build a Go service callable from browsers and gRPC clients
  - Migrate gRPC services to Connect without breaking clients
  - Add HTTP/JSON access to existing Protobuf services
- aid: connect-rpc:connect-es
  name: connect-es (Connect for ECMAScript)
  description: Connect for ECMAScript provides type-safe browser and Node.js clients and Node.js servers from Protobuf schemas.
    Targets the Connect protocol and gRPC-Web with idiomatic TypeScript types and tree-shakable output.
  humanURL: https://connectrpc.com/docs/web/
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  tags:
  - JavaScript
  - SDK
  - TypeScript
  properties:
  - type: Documentation
    url: https://connectrpc.com/docs/web/
  - type: GettingStarted
    url: https://connectrpc.com/docs/web/getting-started
  - type: GitHub
    url: https://github.com/connectrpc/connect-es
  x-features:
  - Browser Clients
  - Node.js Clients
  - Node.js Servers
  - Tree-Shakable Bundles
  - Type-Safe TypeScript
  - gRPC-Web Compatibility
  x-use-cases:
  - Call Protobuf services from React, Vue, or vanilla JS
  - Build Node.js servers without a gRPC dependency
  - Share TypeScript types between client and server
- aid: connect-rpc:connect-swift
  name: connect-swift
  description: Connect for Swift provides type-safe Connect, gRPC, and gRPC-Web clients for iOS, macOS, watchOS, and tvOS
    apps, generated from Protobuf schemas via protoc-gen-connect-swift.
  humanURL: https://connectrpc.com/docs/swift/
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  tags:
  - iOS
  - SDK
  - Swift
  properties:
  - type: Documentation
    url: https://connectrpc.com/docs/swift/
  - type: GettingStarted
    url: https://connectrpc.com/docs/swift/getting-started
  - type: GitHub
    url: https://github.com/connectrpc/connect-swift
  x-features:
  - URLSession Integration
  - Streaming Support
  - gRPC and gRPC-Web Clients
  - Async/Await API
  x-use-cases:
  - Call Protobuf services from iOS apps
  - Add streaming RPC to Apple platform clients
- aid: connect-rpc:connect-kotlin
  name: connect-kotlin
  description: Connect for Kotlin provides type-safe clients for Android and JVM applications. Speaks the Connect protocol,
    gRPC, and gRPC-Web from a single SDK generated by protoc-gen-connect-kotlin.
  humanURL: https://connectrpc.com/docs/kotlin/
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  tags:
  - Android
  - JVM
  - Kotlin
  - SDK
  properties:
  - type: Documentation
    url: https://connectrpc.com/docs/kotlin/
  - type: GettingStarted
    url: https://connectrpc.com/docs/kotlin/getting-started
  - type: GitHub
    url: https://github.com/connectrpc/connect-kotlin
  x-features:
  - Coroutines API
  - OkHttp Transport
  - Streaming Support
  - Multi-Protocol Client
  x-use-cases:
  - Call Protobuf services from Android apps
  - Share Kotlin types across mobile and backend
- aid: connect-rpc:connect-python
  name: connect-python
  description: Connect for Python (beta) provides Connect protocol and gRPC clients generated from Protobuf schemas. Targets
    ASGI servers and async Python with type-safe stubs.
  humanURL: https://connectrpc.com/docs/python/
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  tags:
  - Python
  - SDK
  properties:
  - type: Documentation
    url: https://connectrpc.com/docs/python/
  - type: GitHub
    url: https://github.com/connectrpc/connect-python
  x-features:
  - ASGI Integration
  - Type-Safe Stubs
  - Connect and gRPC Clients
  x-use-cases:
  - Add Protobuf RPC to Python services
  - Call Connect services from data-science notebooks
common:
- type: DomainSecurity
  url: security/connect-rpc-domain-security.yml
- type: Website
  url: https://connectrpc.com
- type: Documentation
  url: https://connectrpc.com/docs/introduction
- type: GitHubOrganization
  url: https://github.com/connectrpc
- type: Demo
  url: https://connectrpc.com/demo
- type: Blog
  url: https://buf.build/blog
- url: https://buf.build/blog/rss.xml
  type: BlogRSS
  description: Discovered RSS/Atom feed for https://buf.build/blog
- type: Maintainer
  url: https://buf.build
- type: License
  url: https://github.com/connectrpc/connect-go/blob/main/LICENSE
- type: Slack
  url: https://buf.build/links/slack
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

Work with this as data

Every provider here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for providers

9 MCP tools reach this

find_providersBrowse and filter every provider in the catalog.
get_provider_artifactsEvery artifact this provider publishes, grouped by type.
get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

All 92 tools →

Call it yourself

curl for this page

This provider

curl "https://apis.io/api/v1/providers/connect-rpc"

All providers

curl "https://apis.io/api/v1/providers?limit=25"

Every operation they expose

curl "https://apis.io/api/v1/providers/connect-rpc/operations?limit=25"

How their score was established

curl "https://apis.io/api/v1/providers/connect-rpc/evidence"

Discovery needs no key. Ratings and market analysis are Pro.

Get an API key

Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.

GitHub Google LinkedIn

A second provider on the same verified email joins the account you already have.