Transcribe

Overview

Transcribes audio or video using AssemblyAI Universal-2/3 models. Returns a structured transcript with optional word timings, speaker labels, sentiment, entities, and content safety flags.

Request

POST /v1/tasks/transcribe
Authorization: Bearer {api_key}

{
  "source_url": "https://cdn.example.com/interview.mp4",
  "language": "en",
  "speech_model": "universal-2",
  "word_timings": true,
  "speaker_labels": true,
  "speakers_expected": 2
}

Key parameters

Parameter	Default	Description
`source_url`	required	URL of the audio or video file
`language`	auto	BCP-47 language code, e.g. `en`, `de`, `es`
`speech_model`	`universal-2`	`universal-2`, `universal-3-pro`, or `nano`
`word_timings`	`true`	Include word-level timestamps
`speaker_labels`	`false`	Enable speaker diarisation
`speakers_expected`	null	Hint for number of speakers (1–10)
`sentiment_analysis`	`false`	Per-sentence sentiment
`entity_detection`	`false`	Named entity recognition
`auto_highlights`	`false`	Extract key phrases
`content_safety`	`false`	Flag sensitive content
`iab_categories`	`false`	IAB taxonomy classification
`word_boost`	`[]`	Domain terms to boost (max 200)

Output

The completed task’s output.url points to a JSON file with the full AssemblyAI transcript response, including text, words, utterances (with speaker labels), and any requested analysis results.

Example output shape

{
  "text": "Welcome back to the show...",
  "words": [
    { "text": "Welcome", "start": 0, "end": 650, "confidence": 0.99, "speaker": "A" }
  ],
  "utterances": [
    { "speaker": "A", "text": "Welcome back to the show.", "start": 0, "end": 2500 }
  ]
}

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​Output

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Overview

Request

Key parameters

Output

Example output shape