Subtitle any video
with three API calls

const API = 'https://autostud.ai/api/v1'
const KEY = process.env.AUTOSTUD_API_KEY

const call = async (path, body) => {
  const response = await fetch(API + path, {
    method: body ? 'POST' : 'GET',
    headers: {
      Authorization: `Bearer ${KEY}`,
      'Content-Type': 'application/json',
    },
    body: body ? JSON.stringify(body) : undefined,
  })

  const payload = await response.json()
  if (!response.ok) throw new Error(payload.error?.message || response.statusText)
  return payload
}

// 1. A video project to hang the timeline on.
const created = await call('/actions/videos.create', {
  video_name: 'Interview clip',
  video_type_id: 'timeline',
  video_format: 'portrait',
  video_lang: 'en',
})
const video_id = created.data.video_id

// 2. Transcribe, emphasise, style — one call.
const subtitled = await call('/actions/subtitles.generate', {
  video_id,
  media_url: 'https://cdn.example.com/interview.mp4',
  style_preset: 'beast',
  words_per_group: 3,
})
console.log(subtitled.data.word_count, 'words', subtitled.data.duration_seconds, 's')

// 3. Render it.
await call('/actions/renders.create', {
  video_id,
  video_type_id: 'timeline',
  video_format: 'portrait',
})

// 4. Wait for the worker. A webhook is better; this is the short version.
let render
do {
  await new Promise((resolve) => setTimeout(resolve, 15000))
  const list = await call(`/renders?video_id=${video_id}&limit=1`)
  render = list.data[0]
} while (render && ['not_started', 'processing'].includes(render.render_status))

if (render.render_status !== 'done') throw new Error('Render failed')
console.log(render.render_url)

Base URL: https://autostud.ai/api/v1 — authenticate with `Authorization: Bearer sk_live_…`. A `sk_test_` key runs the exact same request path and stops before spending anything.

1. 1

   Create an API key

   Dashboard, Settings, API keys. Pick the "Automation" preset unless you want to choose scopes by hand — it grants videos, renders and assets. The secret is shown once. `sk_live_` spends, `sk_test_` validates the whole request and stops before the write.

   curlresponse

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   export AUTOSTUD_API_KEY="sk_live_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
   
   # What can this key actually do?
   curl https://autostud.ai/api/v1 \
     -H "Authorization: Bearer $AUTOSTUD_API_KEY"

2. 2

   Put your video behind a URL

   There is no upload endpoint: the API reads a URL. Your bucket, your CDN, a signed link — anything our servers can fetch. Registering it in the workspace library is optional and does not change the flow.

   curl

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   # The API takes a URL, never a file upload. Anything publicly
   # reachable works: your bucket, your CDN, a signed URL.
   export MEDIA_URL="https://cdn.example.com/interview.mp4"
   
   # Optional: keep a record of it in the workspace library.
   curl -X POST https://autostud.ai/api/v1/assets \
     -H "Authorization: Bearer $AUTOSTUD_API_KEY" \
     -H "Content-Type: application/json" \
     -d '{
       "provider_file_url": "'"$MEDIA_URL"'",
       "provider_file_name": "interview.mp4",
       "file_mime_type": "video/mp4",
       "provider_file_id": "interview-2026-08-18",
       "sync_method": "api"
     }'

3. 3

   Create the video project

   `videos.create` returns the `video_id` everything else hangs off. Send an `Idempotency-Key` and a retried request returns the first answer instead of creating a second project.

   curlresponse

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   curl -X POST https://autostud.ai/api/v1/actions/videos.create \
     -H "Authorization: Bearer $AUTOSTUD_API_KEY" \
     -H "Content-Type: application/json" \
     -H "Idempotency-Key: interview-2026-08-18" \
     -d '{
       "video_name": "Interview clip",
       "video_type_id": "timeline",
       "video_format": "portrait",
       "video_lang": "en"
     }'

4. 4

   Subtitle it

   `subtitles.generate` does the whole job server-side: Whisper transcribes with word-level timings, an AI pass marks the words to emphasise, and one of 116 styles is applied. It answers with the word count, the exact duration and the detected language.

   curlresponse

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   export VIDEO_ID="9f0c4e2a-1d6b-4a77-9d51-6b0f2e8c3a4d"
   
   curl -X POST https://autostud.ai/api/v1/actions/subtitles.generate \
     -H "Authorization: Bearer $AUTOSTUD_API_KEY" \
     -H "Content-Type: application/json" \
     -d '{
       "video_id": "'"$VIDEO_ID"'",
       "media_url": "'"$MEDIA_URL"'",
       "style_preset": "beast",
       "words_per_group": 3,
       "enable_emphasis": true,
       "enable_diarization": false
     }'

5. 5

   Queue the render

   `renders.create` puts the job on the worker fleet and answers immediately with the `render_id`. A render costs 20 credits, whatever the length of the video.

   curlresponse

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   curl -X POST https://autostud.ai/api/v1/actions/renders.create \
     -H "Authorization: Bearer $AUTOSTUD_API_KEY" \
     -H "Content-Type: application/json" \
     -d '{
       "video_id": "'"$VIDEO_ID"'",
       "video_type_id": "timeline",
       "video_format": "portrait"
     }'

6. 6

   Collect the mp4

   Subscribe to `render.completed` and the finished URL is pushed to you, signed. If you would rather pull, list the renders of your video and read `render_status` until it says `done`.

   webhookpollingresponse

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   # Register once, then stop polling.
   curl -X POST https://autostud.ai/api/v1/webhooks \
     -H "Authorization: Bearer $AUTOSTUD_API_KEY" \
     -H "Content-Type: application/json" \
     -d '{
       "url": "https://your-app.com/hooks/autostud",
       "events": ["render.completed", "render.failed"],
       "description": "Subtitled videos"
     }'
   # The signing secret comes back once, in this response. Store it.