AssemblyAI vs Google Cloud Speech-to-Text

For call centers transcribing high volumes, per-minute cost is the deciding factor. AssemblyAI charges $0.0035 per audio minute versus Google Cloud Speech-to-Text at $0.016 per audio minute, a 4.6x price difference that compounds enormously at scale. Diarizationdiarization - Splitting a transcript by speaker, so you can see who said what. is a small add-on for AssemblyAI at $0.000333 per audio minute, while Google Cloud includes it but cannot offset the base rate gap. AssemblyAI also offers PII redaction and built-in sentiment analysis, neither of which Google Cloud provides, and both are critical for call center QA workflows. Concurrency is comparable between the two. The cost advantage plus native analytics features make the choice straightforward.

For developers building transcription into products, pricing is a decisive factor. AssemblyAI charges $0.0035/audio-min for batch processing versus Google Cloud Speech-to-Text at $0.016/audio-min, making AssemblyAI roughly 4.6x cheaper for typical workloads. On streaming, AssemblyAI comes in at $0.0075/audio-min against Google's $0.016/audio-min, again a significant cost gap at scale. Beyond pricing, AssemblyAI offers a WebSocket streaming API while Google Cloud Speech-to-Text does not, which is a hard capability gap for real-time product features. Both tools support word-level timestampsword-level timestamps - The API reports exactly when each word is spoken in the audio, for subtitles and highlighting. equally. On format flexibility, AssemblyAI accepts 30+ audio and video formats compared to Google's smaller set of primarily audio-only formats, giving developers broader ingestion options. SDK breadth favors Google, which publishes libraries in seven languages versus AssemblyAI's two official ones, but this advantage does not outweigh the large pricing gap and the missing WebSocket streaming on Google's side.

For clinical transcription under US healthcare privacy law, a HIPAA BAAHIPAA BAA - A signed Business Associate Agreement that lets you handle protected health information under US healthcare privacy law. is the non-negotiable starting point. Both AssemblyAI and Google Cloud Speech-to-Text offer a HIPAA BAA, so neither is eliminated on that criterion. The deciding factor shifts to PII redaction, which is critical for protecting patient data in transcripts. AssemblyAI offers PII redaction as a paid add-on at $0.001333 per audio minute, while Google Cloud Speech-to-Text has no PII redaction capability at all. That gap alone is significant for a healthcare workflow. Both tools offer custom vocabulary boosting for medical terminology, SOC 2 Type II certification, and self-hosting options, so those attributes are even. AssemblyAI also posts a stronger third-party benchmark accuracy of 3.02% WER versus 4.32% WER for Google Cloud Speech-to-Text, reinforcing its edge for precise clinical documentation.

For recorded meetings and interviews, speaker diarizationdiarization - Splitting a transcript by speaker, so you can see who said what. and summarization are the deciding factors. AssemblyAI offers both, while Google Cloud Speech-to-Text includes diarization but has no summarization endpoint at all. On file length, AssemblyAI handles up to 10 hours per file versus Google Cloud's 8-hour batch limit, giving it an edge for longer all-day recordings. Both tools support word-level timestamps. On languages, Google Cloud claims 125 versus AssemblyAI's 99, so Google edges ahead there, but that advantage is outweighed by the missing summarization feature. Pricing also favors AssemblyAI at $0.0035/audio-min for batch versus Google Cloud's $0.016/audio-min, making large meeting archives significantly cheaper to process.

For a self-hostedself-host - Run the software on your own servers instead of the vendor’s cloud. deployment, the deciding factors are whether each service offers an on-premises option, what license governs the model weights, the hardware needed, and whether the project is actively maintained. Both AssemblyAI and Google Cloud Speech-to-Text confirm that a self-host or on-premises option is available. However, no information is published on model weights licensing, hardware requirements, maintenance status, or model size for either tool. Without those details, it is impossible to distinguish the two on the attributes that matter most for running an open-weight model on your own hardware. The only confirmed shared fact is that both offer self-hosting, leaving the comparison genuinely balanced on available evidence.

For live voice agents, streaming latency and a native WebSocket API are the deciding factors, because they directly determine whether the bot responds naturally or lags the caller. AssemblyAI publishes a 150 ms streaming latency and offers a WebSocket streaming API. Google Cloud Speech-to-Text has no WebSocket streaming API at all, which is a fundamental gap for real-time voice-bot pipelines. On streaming price, AssemblyAI charges $0.0075 per audio minute versus Google Cloud Speech-to-Text at $0.016 per audio minute, making AssemblyAI more than twice as affordable for continuous live sessions. Concurrencyconcurrency - How many phone calls the platform can handle at the same time. is competitive on both sides, and both support custom vocabulary for domain-specific terms. With a hard architectural limitation on streaming transport and a higher per-minute cost, Google Cloud Speech-to-Text cannot match AssemblyAI for this use case.