Soniox vs AssemblyAI speech-to-text
Higher accuracy, real-time fluency, and global reach at lower cost.
Developers choose Soniox for global-ready, real-time fluency
AssemblyAI is known for simple APIs, but for speech itself Soniox outperforms, delivering higher accuracy, true real-time streaming, and global coverage in one API.
With Soniox, you can build one app that works for 8 billion people across 60+ languages. Soniox consistently delivers world-class accuracy, faster real-time streaming, speaker detection, and true multilingual coverage.
Cleaner transcripts, zero mistakes
Benchmarks show Soniox at 6.5% WER in English vs 11.1% for AssemblyAI. Less cleanup, more trust.
One API for 60+ languages
Transcription and translation built in, so your app works worldwide without chaining APIs.
Streaming that feels instant
Token-level results in milliseconds make apps fast, fluid, and human — not robotic.
Helping startups and enterprises ship real world voice apps
See the difference for yourself
Don’t just take our word for it. Run the same audio through Soniox and AssemblyAI in real time and compare live results, side by side.
This demo isn’t pre-recorded. It makes real API calls to AssemblyAI and Soniox in real time, with each service tuned for its best performance. The framework is open source, so you can inspect or run it yourself.
Soniox vs AssemblyAI at a glance
| Feature | Sonioxstt-rt-preview-v2 | AssemblyAIUniversal |
|---|---|---|
| Single Multilingual Model | ||
| Language Hints | ||
| Language Identification | ||
| Speaker Diarization | ||
| Customization | ||
| Timestamps | ||
| Confidence Scores | ||
| Translation One Way | ||
| Translation Two Way | ||
| Endpoint Detection | ||
| Manual Finalization |
And the benchmarks back it up.
In a 2025 study across 60 languages and real-world YouTube audio, Soniox reached 6.5% WER in English vs 11.1% for AssemblyAI.
View the full benchmark report »
Built for accuracy, speed, and scale
Accuracy you can trust in production.
Soniox consistently delivers top results, with a 6.5% WER in English vs 11.1% for AssemblyAI. That means cleaner transcripts, less post-editing, and apps you can actually trust in production.
AssemblyAI lags behind in accuracy, especially as audio gets more complex.
Global ready in one API.
With Soniox, you don’t need to stitch together multiple services. Transcribe and translate in 60+ languages – in real time or async – all from a single API call.
AssemblyAI only handles transcription, so you’ll need extra tools for translation or multilingual support.
Speech-to-text with zero delay.
Soniox streams token-by-token in milliseconds, so conversations feel natural and responsive.
AssemblyAI processes in chunks, creating noticeable delays that break the flow of live apps.
Designed for messy, real-world conversations.
Conversations are messy. People interrupt, switch languages, or talk over each other. Soniox detects speakers, identifies language shifts, and supports endpoint detection out of the box.
AssemblyAI doesn’t support real-time translation or seamless multilingual detection, leaving you to patch it together yourself.
Pay up to 3x less than AssemblyAI
With Soniox, transcription, streaming, translation, diarization, timestamps, and confidence are all included in one price. AssemblyAI charges more for their flagship Universal models, while their lower-cost Nano models come with tradeoffs in accuracy.
Effective hourly cost (typical speech)
Soniox: ~$0.10/hour (async), ~$0.12/hour (streaming)
AssemblyAI: ~$0.27 (universal async), ~$0.15/hr (streaming), ~$0.12/hr (nano async)
| Soniox (async) | Soniox (streaming) | AssemblyAI (nano) | AssemblyAI (universal) | AssemblyAI (streaming) | |
|---|---|---|---|---|---|
| 100 hours | ~$10 | ~$12 | ~$12 | ~$27 | ~$15 |
| 1,000 hours | ~$100 | ~$120 | ~$120 | ~$170 | ~$150 |
| 10,000 hours | ~$1,000 | ~$1,200 | ~$1,200 | ~$1,700 | ~$1,500 |
Takeaway: Soniox costs up to 3x less than AssemblyAI, while including translation and richer real-time features out of the box. AssemblyAI’s cheaper models cut accuracy, while Soniox includes full accuracy and features at one flat rate.
Notes:
- Soniox bills per token, which works out to the effective hourly rates above for typical conversational speech.
- AssemblyAI pricing varies by model. Nano is cheaper but sacrifices accuracy; Universal is higher accuracy but more expensive.
- All comparisons use publicly listed rates as of 2025.
Frequently asked questions about Soniox vs AssemblyAI
How accurate is AssemblyAI compared to Soniox?
In 2025 benchmarks, AssemblyAI had an 11.1% WER on English speech, versus 6.5% for Soniox. That means Soniox produces cleaner transcripts with fewer mistakes to fix, especially as audio gets more complex.
Does AssemblyAI support translation?
No. AssemblyAI only provides transcription. If you need translation, you’ll have to integrate a separate service. Soniox includes two-way real-time translation across 60+ languages in the same API. in-stream translation across 60+ languages in the same API call.
How fast is AssemblyAI’s streaming?
AssemblyAI streams in chunks, which can add noticeable lag in live apps. Soniox streams token-by-token in milliseconds, so conversations feel natural and responsive.
What about multilingual or messy audio?
AssemblyAI is built for transcription only. It doesn’t support automatic language identification, speaker diarization, or endpoint detection in real time. Soniox includes all of these by default, so it works better in real-world, multilingual conversations.
How does AssemblyAI pricing compare to Soniox?
AssemblyAI’s lower-end models are roughly similar in price, but Universal costs nearly 3× more. Soniox stays flat at ~$0.10–0.12/hr with all features included.
Why is Soniox more cost-efficient?
With Soniox, all features are included by default – transcription, translation, diarization, timestamps, and confidence. AssemblyAI charges more for Universal models while still only offering transcription, meaning you’d need additional services to match Soniox’s end-to-end coverage.
Soniox surpasses AssemblyAI in any language
Get the most accurate, real-time speech-to-text transcription and translation in 60+ languages
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