AssemblyAI Speech-to-Text (Universal) vs Google Cloud Speech-to-Text

AssemblyAI Speech-to-Text (Universal)

OpenAPI 3.1 file with typed inputs and error responses on every operation. Two outages of an hour or more in the last 90 days, on 31 July and 16 September 2026.

Google Cloud Speech-to-Text

Audio isn't stored or used for training unless the project opts in to data logging. No release note since 2025-11-13.

AssemblyAI Speech-to-Text (Universal)

1. Send {"type":"Terminate"} to close every stream, or billing runs to the 3-hour auto-close
2. Use speech_models (plural). The singular speech_model now returns 400 for current model names
3. Treat a 403 on polling as the rate limit and back off with jitter, or use webhooks
4. Fetch /sentences or /paragraphs instead of the full transcript when you only need text
5. Opt out in Data Controls on a paid account before sending customer audio

Google Cloud Speech-to-Text

1. Call Chirp 3 on the us or eu endpoint. It isn't listed for the global location
2. Reopen streams before the 5-minute limit, or use BatchRecognize for recordings
3. Downmix stereo unless you need channel labels, since each channel is billed
4. Set dynamic batch on offline jobs to cut the price from $0.016 to $0.003 a minute
5. Back off on RESOURCE_EXHAUSTED. The Speech docs don't give a retry interval