AssemblyAI vs Google Cloud Speech-to-Text

AssemblyAI provides Voice AI models and APIs for speech-to-text, speech understanding, and voice applications. Its Speech Understanding API can identify and diarize speakers, summarize speech, extract action items and key phrases, detect sentiment, entities, and topics, and handle formatting, language detection, translation, PII redaction, and content moderation. The platform lists support for 99 languages and translation into 86. It offers streaming and voice-agent latency below 300ms and states that it processes more than 800 million API calls per month. Use its managed cloud or self-host models in your own environment; the service also lists API access and integrations including Twilio, Zoom RTMS, Zapier, and LangChain. Security options include TLS 1.2+ in transit, AES-256 at rest, zero data retention, and opting out of model training. A free tier is available. Pay-as-you-go billing is based on usage, with monthly invoices and no minimum commitments. Universal-2 is listed at $0.15 per hour of audio; Universal-3.6 Pro Realtime is $0.45 per hour.

Google Cloud Speech-to-Text converts audio into text and provides APIs for adding speech recognition to applications. It offers synchronous, asynchronous, and streaming recognition for post-processing, periodic, or real-time results, and lists support for 85+ languages and variants. Model adaptation lets users provide hints for domain-specific terms, rare words, and phrases. Speaker diarization can predict which speaker produced each utterance; the service also supports multichannel recognition and says it can handle noisy audio without additional noise cancellation. Specialized models are available for voice control, phone calls, and video transcription. API v2 includes data residency, audit logging, and customer-managed encryption keys. Speech-to-Text On-Prem runs in private data centers and is offered through a sales contact. Developer access includes REST and RPC APIs, client libraries, and command-line quickstarts. Listed pricing includes Speech-to-Text V2 API standard recognition models at $0.02 a month, billed at $0.016 / 1 minute for 0–500,000 minutes, with lower rates at higher monthly volumes; V1 standard plans include 60 free minutes per month. Costs depend on duration, channel count, model, batch method, and API version, with each channel billed separately.