AssemblyAI vs IBM Watson Speech to Text
AssemblyAI
assemblyai.com
IBM Watson Speech to Text
ibm.comSide by side
| Figure | AssemblyAI | IBM Watson Speech to Text |
|---|---|---|
| Price from | $0.15/mo | $0.02/mo |
| Free plan | Yes | Yes |
| Free trial | — | Yes |
| Open source | — | — |
| Web | Yes | — |
| API | Yes | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 13 | 5 |
| Spec score · Transcription Software | 8.8 (#8) | 8.7 (#11) |
| Spec score · Speech Recognition Software | 8.8 (#8) | 8.7 (#11) |
| Spec score · AI transcription tools | 8.7 (#13) | 9.0 (#6) |
| Spec score · Audio Transcription Software | 8.8 (#10) | 8.6 (#17) |
| API access | Yes | Yes |
| Export formats | SRT,VTT | JSON |
| Free plan | No | Yes |
| Integrations | Official integrations include LiveKit, Pipecat, OpenRouter, Zapier, Make, n8n, Postman, Recall.ai, Zoom RTMS, Telnyx, Twilio, Amazon Connect, Genesys Cloud, LangChain, Vercel AI SDK, Power Automate, Semantic Kernel, Cloudflare, Bubble, Pipedream, and Drupal. | IBM documents a pre-built phone assistant integration combining watsonx Assistant, Speech to Text, and Watson Text to Speech. |
| Languages supported | 99 | 14 |
| Security | AssemblyAI offers TLS 1.2+ encryption in transit, AES-256 encryption at rest, zero data retention, and an opt-out from model training. | Premium offers data isolation and features including Key Protect, service endpoints, mutual authentication, and HIPAA readiness. |
| Speaker identification | Yes | Yes |
| Timestamp support | Yes | Yes |
| What it does | AssemblyAI provides Voice AI models and APIs for speech-to-text, speech understanding, and voice applications. | The service uses speech recognition APIs to transcribe spoken audio in multiple languages and formats. |
Plans
AssemblyAI
- Free creditsFree
- Pay as you go — Universal-2$0.15 a month
- Pay as you go — Universal-3.5 Pro$0.21 a month
- Pay as you go — Universal-Streaming$0.15 a month
- Pay as you go — Universal-3.5 Pro Realtime$0.45 a month
- Free tierFree
- Universal-2$0.15 a month
- Universal-Streaming$0.15 a month
- Universal-Streaming Multilingual$0.15 a month
- Universal-3.5 Pro$0.21 a month
IBM Watson Speech to Text
- LitePriced on request
- Plus$0.02 a month
- PlusPriced on request
- LiteFree
- PremiumPriced on request
In their own words
AssemblyAI
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.
IBM Watson Speech to Text
IBM Watson Speech to Text has no write-up on Specifiction yet; its figures are above.