Cap'n Proto

Cap'n Proto Encoding (Wire Format)

The Cap'n Proto encoding specification defines the binary wire format. The in-memory layout is the wire format, enabling zero-copy reads and writes, random field access, and safe memory-mapped access to messages stored on disk.

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Specification
https://capnproto.org/encoding.html

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API entry from apis.yml

apis.yml Raw ↑ 
aid: capn-proto:capn-proto-encoding
name: Cap'n Proto Encoding (Wire Format)
description: The Cap'n Proto encoding specification defines the binary wire format. The in-memory layout
  is the wire format, enabling zero-copy reads and writes, random field access, and safe memory-mapped
  access to messages stored on disk.
humanURL: https://capnproto.org/encoding.html
tags:
- Binary Format
- Specification
- Zero-Copy
tags_raw:
- Binary Format
- Specification
- Zero Copy
properties:
- type: Specification
  url: https://capnproto.org/encoding.html
x-features:
- In-memory layout equals the wire format
- Zero-copy deserialization
- Random field access without scanning
- Support for mmap-based message storage
- Packed encoding variant for bandwidth-constrained links
- Canonicalization rules for deterministic encoding
x-use-cases:
- Ultra-low-latency inter-process communication
- Large on-disk datasets with mmap access
- Network protocols where parsing cost matters
- Embedded or memory-constrained environments (packed form)