Soniox vs AssemblyAI
for Czech speech-to-text
Higher accuracy, real-time fluency, and two-way translation for Czech at lower cost.
Developers choose Soniox for real-time fluency in Czech
Czech is spoken by 11 million people worldwide — primarily in Czech Republic, with speakers around the world. For developers, delivering accurate, real-time transcription and translation in Czech is critical. Soniox provides production-ready transcription and two-way translation for Czech, handling regional accents, code-switching, and messy real-world audio.
AssemblyAI is known for simple-to-use APIs, but when it comes to Czech transcription, Soniox outperforms with higher accuracy in real-world audio, true real-time streaming with token-level output in milliseconds, and global coverage with built-in translation across 60+ languages (including Czech) in one API.
Cleaner transcripts
Soniox delivers 9.7% WER in Czech vs 38.2% for AssemblyAI, meaning more accurate Czech transcripts with less cleanup.
One API for 60+ languages
Transcribe and translate Czech and 60+ other languages in real time or async, without stitching multiple APIs.
Streaming that feels instant
Token-level results in milliseconds make Czech conversations fast, fluid, and human.
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 Czech 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
The benchmarks back it up
In a 2025 study across 60 languages and real-world YouTube audio, Soniox reached 9.7% WER in Czech vs 38.2% for AssemblyAI.
View the full benchmark reportFeature | Sonioxstt-rt-v3 | AssemblyAIUniversal |
---|---|---|
open_in_newSingle Multilingual Model | check | close |
open_in_newLanguage Hints | check | close |
open_in_newLanguage Identification | check | close |
open_in_newSpeaker Diarization | check | close |
open_in_newCustomization | check | close |
open_in_newTimestamps | check | check |
open_in_newConfidence Scores | check | check |
open_in_newTranslation One Way | check | close |
open_in_newTranslation Two Way | check | close |
open_in_newEndpoint Detection | check | check |
open_in_newManual Finalization | check | check |
“It just gets the words right — any language, any accent, any context. That’s what accuracy is supposed to look like.”
Tony Wang,
Cofounder & Chief Revenue Officer at Agora
Built for accuracy, speed, and scale
Accuracy you can trust in production.
Soniox consistently delivers top results for Czech, with a 9.7% WER in Czech vs 38.2% 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.
Soniox includes transcription and two-way translation for Czech and 60+ languages, plus speaker detection, timestamps, and diarization – all in one API.
AssemblyAI only handles transcription, forcing developers to chain extra services for translation or multilingual coverage.
Speech-to-text with zero delay.
Soniox streams token-by-token in milliseconds, so Czech conversations feel live and human.
AssemblyAI processes in chunks, creating noticeable delays that break the flow of live apps.
Designed for messy, real-world conversations.
Soniox handles real-world speech: speaker changes, interruptions, code-switching, and multilingual shifts in Czech.
AssemblyAI doesn't support real-time translation, diarization, or multilingual detection, leaving you to patch it together.
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)
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.
- 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.
Fluent at any speed
Watch Soniox keep up with fast speech in any language
Frequently asked questions about Soniox vs AssemblyAI
1.How accurate is AssemblyAI in Czech compared to Soniox?arrow_downward
2.Does AssemblyAI support Czech translation?arrow_downward
3.How fast is AssemblyAI's streaming?arrow_downward
4.What about multilingual or messy audio?arrow_downward
5.How does AssemblyAI pricing compare to Soniox?arrow_downward
6.Why is Soniox more cost-efficient?arrow_downward
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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