Cassini/format

Reference

The format, fully specified.

The contracts and tools for building compatible readers and producers. Start with v1, then follow the body format and verification rules it references.

Current version · Published 2 September 2026

Cassini v1

The file structure, metadata, producer requirements and reader behavior.

org.cassini.portable-meeting/1

The supporting contracts

01

Transcript body

A word, its speaker, and start and end times in milliseconds.

cassini.words.v1
 02

Audio digest

The exact bytes used to match a transcript to a recording, independent of its tags.

exact-opus-audio-v1

Validate your implementation

Schemas check the JSON shape. Conformance vectors exercise the behavior of a reader.

Cassini Portable Meeting Manifest v1cassini-portable-meeting-manifest-v1.schema.json15.2 KB ↗Cassini transcript body (cassini.words.v1)cassini-words-v1.schema.json3.2 KB ↗
About the schemas →Conformance suite on GitHub ↗Download an example file ↓

A little more context

The guides walk through an implementation. Design notes explain the decisions behind the contract.

Specification text: CC BY 4.0. Schemas, test vectors and standalone readers/producer: CC0. The gocassini reference application and the site's Cassini transcript component are AGPL-3.0.