HTTP/2’s multiplexing and binary framing make it significantly more efficient than HTTP/1.1, reducing latency and improving throughput. Connect RPC lets you harness these benefits while maintaining broad client compatibility for services that can’t yet support HTTP/2.

Connect RPC can be used to build both internal and external APIs, powering frontends, mobile apps, CLIs, agents and more. See the list of supported languages.

Core Features

Connect RPC provides a number of features out of the box, such as:

• Interceptors which make it easy to extend Connect RPC and are used to add authentication, logging, metrics, tracing and retries.
• Serialization & compression, with pluggable serializers, and support for asymmetric compression reducing the amount of data that needs to be transmitted, or received.
• Error handling, with a standard error format, with support for custom error codes to allow for more granular error handling.
• Observability, with in built support for OpenTelemetry enabling you to easily add tracing, or metrics to your APIs.
• Streaming, which provides a very efficient way to push or pull data without polling.
• Schemas, which enable you to define and validate your API schemas, and generate code from them.
• Code generation for Go, TypeScript, Kotlin, Swift and Java.

Ecosystem

In addition to these features, Connect RPC is built on top of the Buf ecosystem, which offers notable benefits:

• Connect RPC joins CNCF, entering the cloud-native ecosystem, which is great for the long term sustainability of the project.
• Buf Schema Registry, which is a great tool for managing, sharing and versioning your API schemas.
• Buf CLI, a handy all in one tool for managing your APIs, generating code and linting.

Recommended Interceptor Packages

Some handy Go packages that provide pre-built Connect RPC interceptors worth exploring or using as a starting point:

• authn-go, provides a rebuilt authentication middleware library for Go. It works with any authentication scheme (including HTTP basic authentication, cookies, bearer tokens, and mutual TLS).
• validate-go provides a Connect RPC interceptor that takes the tedium out of data validation. This package is powered by protovalidate and the Common Expression Language.
• rpclog provides a structured logging interceptor for Connect RPC with support for both unary and streaming RPCs.

Summary

1. Connect RPC provides a paved and well maintained path to building gRPC compatible APIs, while maintaining compatibility for HTTP/1.1 clients. This is invaluable for product teams that need to support multiple client types without building custom compatibility layers.

2. Using a mature library like Connect RPC, you get to benefit from all the prebuilt integrations, and the added capabilities of the Buf ecosystem. This makes publishing and consuming APIs a breeze.

3. Protobuf schemas, high performance serialisation and compression ensure you get robust and efficient APIs.

Conclusion

Connect RPC makes it easy to build high-performance, robust APIs with gRPC compatibility, while avoiding the complexity of building and maintaining custom compatibility layers.