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

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

Feature	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, 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.

Start building with Soniox arrow_right_alt

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.

Start building with Soniox arrow_right_alt

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)

100 hours

1,000 hours

10,000 hours

Soniox (async)

~$10

~$100

~$1,000

Soniox (streaming)

~$12

~$120

~$1,200

AssemblyAI (nano)

~$12

~$120

~$1,200

AssemblyAI (universal)

~$27

~$170

~$1,700

AssemblyAI (streaming)

~$15

~$150

~$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.

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

Chinese to English in real time with SONIOX

Very fast speaking Spanish translated in real time in English with SONIOX!

Real time translation from Japanese to English

Real-Time Translation Demo | From German to English with SONIOX

French speech to Text | Leslie Talks About Monster eating a Cake

Russian to English with SONIOX

Speaking Super Fast in Italian – Soniox still translated every word into English

Korean to English in real time with SONIOX

Real-Time from Slovenian to English with SONIOX

Valeria Juri Reads Ukrainian Poem “Мовчати” | Live English Translation by Soniox

Frequently asked questions about Soniox vs AssemblyAI

1.How accurate is AssemblyAI compared to Soniox?arrow_downward

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.

2.Does AssemblyAI support translation?arrow_downward

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.

3.How fast is AssemblyAI's streaming?arrow_downward

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.

4.What about multilingual or messy audio?arrow_downward

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.

5.How does AssemblyAI pricing compare to Soniox?arrow_downward

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.

6.Why is Soniox more cost-efficient?arrow_downward

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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