Deepgram Speech-to-Text (Nova-3, Flux) vs Rev AI Speech-to-Text API

Deepgram Speech-to-Text (Nova-3, Flux)

Flux streams with model-level end-of-turn detection, so a voice agent needs no separate VAD. Training on audio is the default and the opt-out is a per-request flag.

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.

Deepgram Speech-to-Text (Nova-3, Flux)

1. Add mip_opt_out=true to every request that carries customer audio
2. Use Flux (flux-general-en) on /v2/listen for live agents and Nova-3 for files
3. Back off exponentially on 429. The concurrency limit is per project
4. Pass callback for long files so the request doesn't hit the 10-minute processing timeout
5. Mint keys with an expiry for short-lived jobs

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