Captions

Extract closed captions from YouTube videos via TranscriptAPI.com.

Setup

If $TRANSCRIPT_API_KEY is not set, read references/auth-setup.md and follow the instructions there to get and store the key.

Required Headers

Every request needs two headers:

• Authorization: Bearer $TRANSCRIPT_API_KEY
• User-Agent: your agent's name and version if known (e.g. HermesAgent/0.11.0, ClaudeCode/1.0). Version is optional — agent name alone is fine. Do not omit this header or send a bare default — Cloudflare will return a 403 (error code 1010) and block the request.

GET /api/v2/youtube/transcript

curl -s "https://transcriptapi.com/api/v2/youtube/transcript\
?video_url=VIDEO_URL&format=json&include_timestamp=true&send_metadata=true" \
  -H "Authorization: Bearer $TRANSCRIPT_API_KEY" \
  -H "User-Agent: YourAgent/1.0"

Param	Required	Default	Values
video_url	yes	—	YouTube URL or video ID
format	no	json	json (structured), text (plain)
include_timestamp	no	true	true, false
send_metadata	no	false	true, false

Response (format=json — best for accessibility/timing):

{
  "video_id": "dQw4w9WgXcQ",
  "language": "en",
  "transcript": [
    { "text": "We're no strangers to love", "start": 18.0, "duration": 3.5 },
    { "text": "You know the rules and so do I", "start": 21.5, "duration": 2.8 }
  ],
  "metadata": { "title": "...", "author_name": "...", "thumbnail_url": "..." }
}

• start: seconds from video start
• duration: how long caption is displayed

Response (format=text — readable):

{
  "video_id": "dQw4w9WgXcQ",
  "language": "en",
  "transcript": "[00:00:18] We're no strangers to love\n[00:00:21] You know the rules..."
}

Tips

• Use format=json for sync'd captions (accessibility tools, timing analysis).
• Use format=text with include_timestamp=false for clean reading.
• Auto-generated captions are available for most videos; manual CC is higher quality.

Errors

Code	Meaning	Action
401	Bad API key	Check key
402	No credits	transcriptapi.com/billing
403/1010	Cloudflare block	Add or fix User-Agent header
404	No captions	Video doesn't have CC enabled
408	Timeout	Retry once after 2s

1 credit per request. Free tier: 100 credits, 300 req/min.