Rev AI Speech-to-Text API vs Speechmatics Speech-to-Text

Rev AI Speech-to-Text API

Reverb English at $0.20 an hour, foreign languages at $0.30. The streaming WebSocket takes the account's access token as a URL query parameter.

Speechmatics Speech-to-Text

Training is opt-in and real-time audio is not stored. Enhanced transcription costs $0.40 to $0.43 an hour.

Rev AI Speech-to-Text API

1. Keep streaming URLs out of logs. They carry access_token
2. Send source_config: {"url": ...}, not media_url, even though the published SDKs still use media_url
3. Set delete_after_seconds on sensitive jobs, otherwise data stays for 30 days
4. Use notification_config webhooks rather than polling job status
5. Don't build on low_cost or fusion. Both are deprecated

Speechmatics Speech-to-Text

1. Set "model": "enhanced" explicitly. The default is standard
2. Use notifications instead of polling. Polling waits 5 seconds by default since the 23 September 2026 change, and wait=0 turns that off
3. Fetch batch transcripts within 7 days. After that the API returns 404 expired
4. Pass a fetch_data URL for files over 1 GB
5. Use /v2/agent with linden-1 for live agents instead of the plain realtime path