Connect RPC
Better gRPC-compatible RPC framework that works over HTTP/1.1, HTTP/2, and in browsers. Connect is a protocol by Buf that generates servers and clients in Go, TypeScript, Kotlin, and Swift from Protobuf definitions. Unlike gRPC-Web, Connect RPC works natively in browsers without a proxy. Combines Protobuf's efficiency with REST-like browser compatibility for agent communication protocols.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
TLS strongly recommended. Protobuf schema provides type safety. Interceptors for auth, audit, and request validation. No built-in auth layer.
⚡ Reliability
Best When
You want Protobuf-typed APIs that work in browsers without proxies, with Go and TypeScript code generation from Protobuf definitions.
Avoid When
You prefer REST/JSON, don't want the Protobuf toolchain, or need compatibility with gRPC clients that only speak gRPC binary protocol.
Use Cases
- • Build type-safe agent API protocols using Protobuf with browser-compatible HTTP/1.1 and HTTP/2 support
- • Replace REST APIs in agent services with Connect RPC for strongly-typed request/response schemas
- • Enable browser-based agent UIs to call Protobuf services directly without gRPC-Web proxy infrastructure
- • Build streaming agent APIs (server-streaming, bidirectional) that work in both browser and server contexts
- • Standardize agent service interfaces across Go, TypeScript, and mobile clients from single Protobuf definition
Not For
- • Teams not using Protobuf — Connect requires Protobuf schema-first approach
- • Simple CRUD APIs — REST + JSON is simpler without Protobuf toolchain overhead
- • Existing gRPC services that need gRPC-only binary protocol — Connect speaks gRPC but adds Connect protocol
Interface
Authentication
No built-in auth — implements via interceptors (middleware equivalent for Connect). Common: Bearer token in Authorization header.
Pricing
Completely free and open source, maintained by Buf.
Agent Metadata
Known Gotchas
- ⚠ Connect protocol, gRPC, and gRPC-Web are three distinct protocols — Connect servers support all three but clients must choose which to speak
- ⚠ Protobuf toolchain (buf CLI or protoc) required to generate code from .proto files — adds build pipeline complexity
- ⚠ Streaming RPCs (server-stream, bidi) require HTTP/2 — browser clients using HTTP/1.1 can only use unary and server-streaming
- ⚠ Connect's JSON protocol uses field names from Protobuf options — proto field names vs JSON names can differ depending on json_name options
- ⚠ Interceptors replace middleware — Connect's interceptor API is different from http.Handler middleware; existing HTTP middleware doesn't compose directly
- ⚠ Generated client code is version-coupled to buf generate configuration — updating Protobuf definitions requires regenerating all client code
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for Connect RPC.
Scores are editorial opinions as of 2026-03-06.