API Documentation

Captain Transcribe API v1 — transcribe audio and video files programmatically.

API access is available on the Pro plan. Generate your API key in Settings.

Authentication

All API requests must include your API key in the Authorization header as a Bearer token.

curl https://captaintranscribe.com/api/v1/transcriptions \
  -H "Authorization: Bearer ct_your_api_key_here"

Your API key starts with ct_. Keep it secret — do not expose it in client-side code.

Keys expire after one year and can be revoked or regenerated immediately from Settings.

POST /api/v1/transcribe

Transcribe an audio or video file. This endpoint waits until processing is complete before returning the response.

Idempotency-Key is required. Reuse the same value when retrying the exact same upload; use a new value for a different request.

Request

Send a multipart/form-data request with the following fields:

Field	Type	Required	Description
file	File	Yes	Audio or video file (MP3, WAV, MP4, etc.)
language	string	No	Language code (for example "fr" or "en"). Default: "auto"
speakerDetection	string	No	Set to "true" to enable speaker detection

Example

curl -X POST https://captaintranscribe.com/api/v1/transcribe \
  -H "Authorization: Bearer ct_your_api_key_here" \
  -H "Idempotency-Key: 550e8400-e29b-41d4-a716-446655440000" \
  -F "file=@interview.mp3" \
  -F "language=fr" \
  -F "speakerDetection=true"

Response

{
  "id": "abc123",
  "text": "Full transcription text...",
  "segments": [
    { "start": 0.0, "end": 3.5, "text": "Hello world" }
  ],
  "words": [
    { "start": 0.0, "end": 0.5, "word": "Hello" },
    { "start": 0.6, "end": 1.0, "word": "world" }
  ],
  "language": "en",
  "duration": 125.4,
  "speakers": [
    {
      "label": "A",
      "segments": [{ "start": 0.0, "end": 3.5, "text": "Hello world" }]
    }
  ]
}

The speakers field is present only when speaker detection is enabled. The X-Quota-Minutes-Remaining header shows the remaining quota in minutes.

GET /api/v1/transcriptions

List your transcriptions with pagination.

Query parameters

Parameter	Default	Description
limit	20	Number of results (maximum 100)
cursor	—	Opaque cursor returned as nextCursor by the previous page

Example

curl https://captaintranscribe.com/api/v1/transcriptions?limit=10 \
  -H "Authorization: Bearer ct_your_api_key_here"

Response

{
  "transcriptions": [
    {
      "id": "abc123",
      "fileName": "interview.mp3",
      "language": "fr",
      "duration": 125.4,
      "createdAt": "2026-04-01T10:30:00.000Z"
    }
  ],
  "limit": 10,
  "count": 1,
  "nextCursor": null
}

GET /api/v1/transcription/:id

Get the full transcription result by ID.

Example

curl https://captaintranscribe.com/api/v1/transcription/abc123 \
  -H "Authorization: Bearer ct_your_api_key_here"

Response

{
  "id": "abc123",
  "text": "Full transcription text...",
  "segments": [...],
  "words": [...],
  "language": "fr",
  "duration": 125.4
}

Rate limits

Limit	Value
Concurrent transcriptions	3
Transcription requests per hour	60
Concurrent read requests	10
Read requests per hour	300
Monthly quota (Pro plan)	2400 minutes (40 hours)
Maximum file size	95 MB

The X-Quota-Minutes-Remaining response header shows your remaining quota in minutes after each transcription.

Error handling

Every error returns a JSON object with an error field.

Status	Meaning
400	Bad request (missing file or invalid format)
401	Invalid or missing API key
403	Quota exceeded or plan not eligible
404	Transcription not found
429	Rate limit exceeded
500	Server error

Example error response

{
  "error": "Monthly quota exceeded"
}