AUDIO to VTT
Convert audio files to WebVTT subtitle files for web players. Supports three transcription modes — fast, quality, and meeting intelligence — with configurable output formats.
Try Audio to VTT in the browser →
Convert.FAST uses this same API — what you see in the browser is what you get in code.
Quick reference
| Job type | audio.audio-to-vtt |
| targetFormat | vtt |
| Category | audio |
| Input formats | .mp3, .wav, .m4a, .flac, .ogg, .opus, .aac, .webm, .mp4, .mkv, .mov, .avi |
| Output extension | .vtt |
| Costing | 2 credit per minute |
| Cost by transcription mode | Fast: 2 credits/minute (default) · Quality: 5 credits/minute · Meeting Intelligence: 8 credits/minute |
| Max file size | 1 GB |
| Max duration | 300 min |
Example
# 1) Submit
JOB_ID=$(curl -sS -X POST "https://api.tools.fast/convert" \
-H "X-Fast-Api-Key: $API_KEY" \
-F "file=@audio.mp3" \
-F "targetFormat=vtt" | jq -r '.id')
# → 202 Accepted: {"id": "019e3a7b-...", "status": "Queued"}
# 2) Poll until terminal status
while true; do
RESPONSE=$(curl -sS "https://api.tools.fast/convert/job/${JOB_ID}" \
-H "X-Fast-Api-Key: $API_KEY")
STATUS=$(echo "$RESPONSE" | jq -r '.status')
[ "${STATUS}" = "Succeeded" ] && break
[ "${STATUS}" = "Failed" ] || [ "${STATUS}" = "Canceled" ] && { echo "$RESPONSE" | jq; exit 1; }
sleep 1
done
# 3) Download
curl -sS "https://api.tools.fast/convert/job/${JOB_ID}/download" \
-H "X-Fast-Api-Key: $API_KEY" \
-o "audio.vtt"
# → Binary file (text/vtt, 1.2 MB)Options
This converter supports the following options. See Options Reference for full details.
| Option | Description | Default |
|---|---|---|
transcription | Audio transcription settings — mode, output formats, and primary format | mode: fast, includeTxt: false, includeSrt: false, includeVtt: false, includePdf: false, includeDocx: false, includeMarkdown: false, includeEpub: false |
Multi-format output: Audio transcription can produce multiple formats in a single job. The endpoint you call sets the primary format; use the
include*flags to add additional formats. See Options Reference for all available settings.
Cost estimate
curl -sS "https://api.tools.fast/convert/estimate/mp3/vtt?durationMinutes=10"
# With transcription mode variant (Meeting Intelligence)
curl -sS "https://api.tools.fast/convert/estimate/mp3/vtt?durationMinutes=10&variant=meeting-intelligence"