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API

Subtitle API for developers

Add automatic video subtitles to your product with a REST API: submit a video, check its status with a single GET and download subtitle files or a video with burned-in captions.

Read the documentation โ†’

How the API works

Get a key

Create a key in the Developers section of your account. It is shown once and sent as a Bearer token.

Submit a video

Pass a link to a video file or a YouTube video โ€” or upload the file: with PUT to a signed URL or through the API itself.

Poll the job

No emails, no webhooks to wire up: one GET returns status, progress and the credits actually spent.

Download

SRT, VTT or ASS โ€” or a video with burned-in captions: MP4, MOV, MP4 H.265 or WebM, in any style from the template library.

A subtitle job in three requests

# 1. Submit a video โ€” one request runs the whole pipeline
POST /v1/videos { "url": "โ€ฆ", "style": "neon" }

# 2. Poll until status is ready (the API sends no email)
GET  /v1/videos/{id}

# 3. Order the file, then pick up the link from GET โ€ฆ/exports
POST /v1/videos/{id}/exports { "format": "mp4" }

Every request carries the Authorization: Bearer cs_live_โ€ฆ header. Base URL โ€” https://api.captions.space.

Every endpoint

RequestWhat it does
GET
/v1/me		Plan, credit allowance and what is left
GET
/v1/styles		Design templates โ€” the id for the style field
GET
/v1/formats		Export formats and their file extensions
POST
/v1/videos		Create a video; with a url the run starts right away, without one you get an upload_url
POST
/v1/videos/{id}/file		Upload the file through the API (multipart) instead of PUT to upload_url
POST
/v1/videos/{id}/start		Start processing an uploaded file
GET
/v1/videos		Videos in the account, newest first
GET
/v1/videos/{id}		Status, progress, error and the actual credit charge
DELETE
/v1/videos/{id}		Delete a video and its files
POST
/v1/videos/{id}/exports		Order a file in a format and, optionally, another style
GET
/v1/videos/{id}/exports		Ready files with download links

API and editor work together

  • Videos created through the API land in your account: open any of them in the editor to fix a word or a timing.
  • Design added in the editor โ€” text templates, your own watermark โ€” goes into the next video file you order through the API.
  • Credits are shared: the editor and the API spend one balance.

Credits instead of a price list

  • One credit covers one started minute of processed video.
  • Pro includes 1000 credits per 30-day subscription period, shared with the editor; the allowance renews on the day you renew, not on the 1st.
  • Videos up to 30 minutes. A video longer than your remaining balance is refused with a clear error code instead of being cut.
  • A failed run costs nothing, and downloading or re-styling a finished video costs nothing either.

The API is part of the Pro plan: keys are not issued on the Free and Lite plans.

See plans โ†’

Beautiful captions.
Better videos.

Captions Space generates AI subtitles, styles them with designer presets and exports the finished video.

Create captions โ†’

No credit card required

  • โœ“ Free plan available
  • โœ“ One-click instant export
  • โœ“ Built for creators

Runs in the browser โ€” no install, no credit card, and a free plan with 6 minutes of video a month.