# Cap'n Proto Schema Language

**Canonical:** https://apis.io/apis/capn-proto/capn-proto-schema-language/  
**Provider:** Cap'n Proto — https://apis.io/providers/capn-proto/  
**Documentation:** https://capnproto.org/language.html

Cap'n Proto Schema Language is one of 5 APIs that [Cap'n Proto](https://apis.io/providers/capn-proto/) publishes on the [APIs.io](https://apis.io/) network. Tagged areas include Code Generation, Schema, and Specification. The published artifact set on APIs.io includes API documentation and a GitHub repository.

The Cap'n Proto schema language is used to define message types in .capnp files that are then compiled into native code for each supported language. The schema language defines structs, unions, enums, interfaces (for RPC), groups, generics, and annotations, and carefully specifies evolution rules so schemas can be extended without breaking forward or backward compatibility.

## Machine-readable artifacts (4)

- **Specification** — https://capnproto.org/language.html
- **Documentation** — https://capnproto.org/language.html
- **GitHubRepository** — https://github.com/capnproto/capnproto
- **APIsJSON** — https://raw.githubusercontent.com/api-evangelist/capn-proto/refs/heads/main/apis.yml

## Other Cap'n Proto APIs (4)

- [Cap'n Proto Encoding (Wire Format)](https://apis.io/apis/capn-proto/capn-proto-encoding/)
- [Cap'n Proto RPC Protocol](https://apis.io/apis/capn-proto/capn-proto-rpc/)
- [Cap'n Proto C++ Reference Implementation](https://apis.io/apis/capn-proto/capn-proto-cpp-runtime/)
- [Cap'n Proto Language Bindings](https://apis.io/apis/capn-proto/capn-proto-language-bindings/)

## Tags

Code Generation, Schema, Specification

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/apis/capn-proto/capn-proto-schema-language/). The API's provider profile, Kin Score and agent-readiness rating are at https://apis.io/providers/capn-proto/.