Overview and quickstart

1. Get an API key

In the app, open Settings → API keys and create a key. Keys look like chk_live_… and are shown once, so store yours somewhere safe (an environment variable is perfect).

• API access is included on Plus and above. Compare plans.
• Videos made with an API key, through the API, the SDK and CLI or the key-based MCP server, use your plan minutes at 2x: a 1-minute video uses 2 minutes. The connector for Claude and other assistants, which signs in to your account, works on every plan and counts like the app.

2. Authenticate

Send the key as a bearer token on every request:

Authorization: Bearer chk_live_...

All request and response bodies are JSON. The API lives at https://app.trychasca.com/api.

3. Create an explainer

Send what you want explained as input: a topic, a question or the full text of a document. Pick a length in 30-second steps up to 30:00, or leave it out and Chasca chooses.

curl -X POST https://app.trychasca.com/api/v1/explainer \
  -H "Authorization: Bearer $CHASCA_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "input": "Explain how vaccines train the immune system",
    "length": "1:00",
    "aspect": "16:9",
    "preset": "marker"
  }'

The API answers 202 Accepted straight away with the queued record. Generation runs in the background.

{
  "id": "0b9c6f2e-5d1a-4c3e-9a47-2f8e1c7d4b60",
  "status": "queued",
  "stage": null,
  "progress": 0,
  "prompt": "Explain how vaccines train the immune system",
  "lengthSeconds": 60,
  "voice": "chasca:sulafat",
  "language": "en",
  "aspect": "16:9",
  "preset": "marker",
  "videoUrl": null,
  "createdVia": "api",
  "createdAt": "2026-09-23T09:14:02.118Z"
}

4. Wait for it

Poll the explainer until status is ready. It moves through queued → generating → rendering → ready (or failed, with a readable error). Most videos are ready in under a minute. If you’d rather not poll, subscribe to the event stream.

curl https://app.trychasca.com/api/v1/explainer/0b9c6f2e-5d1a-4c3e-9a47-2f8e1c7d4b60 \
  -H "Authorization: Bearer $CHASCA_API_KEY"

A ready explainer carries videoUrl, posterUrl and subtitlesUrl, plus the full editable sceneGraph, every version and per-scene timings. Media links are signed and expire after about a week; fetch the explainer again for fresh ones.

5. Change one thing

Send one change, and everything else stays exactly as it was. Subtitles, board style, music, watermark, logo and credit line make a free new version of the same video, with the same narration. A new voice or format makes a separate video from the same script and drawings, charged like a new one.

curl -X POST https://app.trychasca.com/api/v1/explainer/0b9c6f2e-5d1a-4c3e-9a47-2f8e1c7d4b60/change \
  -H "Authorization: Bearer $CHASCA_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "kind": "captions", "captions": true, "captionStyle": "bold" }'

To change the words or the drawings, send the explainer’s sceneGraph back with your edits to edit: only the scenes that changed are drawn again. Undo either with revert.

Prefer TypeScript?

The SDK wraps all of this, including waiting, retries and typed responses. See CLI and SDK. To let Claude, Cursor or another agent drive Chasca, see MCP setup.

import { ChascaClient } from '@chasca/sdk';

const chasca = new ChascaClient({ apiKey: process.env.CHASCA_API_KEY! });

const job = await chasca.createExplainer({ input: 'How compound interest snowballs', length: '1:00' });
const video = await chasca.waitForExplainer(job.id);
console.log(video.videoUrl);

Limits at a glance

• Generation, change and edit requests: 20 per minute. Everything else: 200 per minute.
• Video length: 30 seconds to 30 minutes, in 30-second steps. Past 6 minutes a video is told in chapters, and your minutes left have to cover the length you ask for.
• Errors always look the same: { "error": true, "code": "...", "message": "...", "status": 400 }. See errors.