The .curt format.

.curt is an open, single-file format for AI chat conversations: one file, one conversation, full fidelity — images and tool calls ride verbatim. Born in Curtis AI Chat, specified openly so any app can read and write it. Your history is files, not hostages.

.CURT — THE GUARANTEE

WHY THE FORMAT CAN BE TRUSTED

shapeone file, one conversation, UTF-8 JSON

fidelitybase64 images and tool calls survive verbatim

validationstrict — a corrupted file is rejected whole, never half-imported

licenseMIT — zero dependencies in the reference reader

File shape.

A .curt file is UTF-8 JSON (tab-indented by convention). The generator field lets your app sign what it wrote — readers must ignore it.

{
  "curt": "curtis-conversation",
  "version": 1,
  "generator": "[email protected]",
  "conversation": { ... }
}

Writers may attach extra fields anywhere — tokens, images, tool-call linkage — and readers must preserve them on round-trip and never fail on them. The full field tables live in the spec.

Validation, version 1.

A reader accepts a file as .curt v1 when, and only when, the body parses as JSON, the magic field is exactly "curtis-conversation" with version 1, and the conversation carries its id, title, timestamps, and a messages array in which every entry passes message validation. Anything else is a rejection — whole-file, not a best-effort parse.

Multiple conversations travel as a zip of .curt files. Versions change rarely and only additively within a version; version-1 files stay readable forever.

Read and write it.

The reference implementation is TypeScript, zero dependencies, MIT:

npm install curt-format

import { serializeCurt, parseCurt } from 'curt-format';

const body = serializeCurt(conversation, '[email protected]');
const back = parseCurt(body); // CurtConversation | null — null means invalid

curt-format on npm · dot_curt repository · SPEC.md · round-trip fixtures

Third-party writers are welcome. PRs for bindings in other languages too — keep the reference implementation and the spec in lockstep.