# AssemblyAI vs Soniox

> AssemblyAI vs Soniox: AssemblyAI is our pick, leading for medical and meetings. They split on streaming latency and languages supported. Verified July 2026.

![AssemblyAI logo](https://www.versusref.com/logos/assemblyai.png) ![Soniox logo](https://www.versusref.com/logos/soniox.png)

This is the verified AssemblyAI vs Soniox breakdown: AssemblyAI (Accuracy-led voice AI API for developers and voice agents) and Soniox (Ultra-low-cost multilingual STT + real-time translation API) are Speech-to-text APIs platforms, priced from $0.0035/min and $0.0017/min respectively. The bottom line, head-to-head facts, and true cost tiers follow.

Speech-to-text APIs platforms · 31 facts compared · all sourced · pricing verified Jul 20, 2026

## Bottom line

AssemblyAI wins four of five use cases, with only Dictation ending in a tie. In Medical and Meetings, its third-party benchmark of 3.02% WER beats Soniox's 3.81%, and its 200-plus concurrent async jobs dwarf Soniox's 10 concurrent websocket sessions, making it far more scalable for high-volume workflows. For Voice Agents, AssemblyAI's vendor-claimed 150 ms streaming latency edges Soniox's 249 ms, and it adds entity detection, sentiment analysis, and summarization that Soniox lacks entirely. In Self-Hosted, AssemblyAI supports on-premises deployment while Soniox offers no self-host option. AssemblyAI also provides a $50 signup credit with no credit card required, while Soniox discontinued free credits in 2025.

## Verdict summary

| Use case | Winner | Why |
| --- | --- | --- |
| Dictation | Tie | The available facts cover API-level attributes such as batch pricing, streaming latency, WER, diarization, and compliance, but none address the attributes that decide the dictation use case: platform support for voice typing apps, local versus cloud audio processing, AI formatting and editing features, one-time versus subscription app pricing, or app integrations. |
| Medical | AssemblyAI | Both tools offer a HIPAA BAA and SOC 2 Type II certification, making them equal on the two highest-weighted compliance requirements. |
| Meetings | AssemblyAI | For recorded meetings and interviews, speaker diarization and summarization carry the most weight. |
| Self-Hosted | AssemblyAI | For a self-hosted deployment, the single most critical factor is whether a vendor actually offers a self-host or on-prem option. |
| Voice Agents | AssemblyAI | For voice agents, streaming latency is the top-weighted factor. |

## AssemblyAI vs Soniox: head-to-head facts

| Fact | AssemblyAI | Soniox | Verified |
| --- | --- | --- | --- |
| Batch price per audio minute | 0.004 $/audio-min ([source](https://www.assemblyai.com/pricing)) | 0.002 $/audio-min ([source](https://soniox.com/pricing)) | Jul 20 |
| Streaming price per audio minute | 0.008 $/audio-min ([source](https://www.assemblyai.com/pricing)) | 0.002 $/audio-min ([source](https://soniox.com/pricing)) | Jul 20 |
| Free tier quota | $50 one-time signup credit, no credit card required ([source](https://www.assemblyai.com/llms/pricing.md)) | None - free credits discontinued 2025-10 ([source](https://soniox.com/blog/2025-10-27-free-credits-update-for-soniox-api)) | Jul 20 |
| WER (third-party benchmark) | 3.02 % WER ([source](https://artificialanalysis.ai/speech-to-text)) | 3.81 % WER ([source](https://artificialanalysis.ai/speech-to-text)) | Jul 20 |
| Streaming latency (vendor-claimed) | ~150 ms ([source](https://www.assemblyai.com/llms/models.md)) | ~249 ms ([source](https://soniox.com/benchmarks)) | Jul 20 |
| Languages supported | 99 ([source](https://www.assemblyai.com/docs/pre-recorded-audio/supported-languages)) | 60 languages ([source](https://soniox.com/docs/stt/concepts/supported-languages)) | Jul 20 |
| Speaker diarization | ◑  Paid add-on ([source](https://www.assemblyai.com/pricing)) | ✓  Included ([source](https://soniox.com/pricing)) | Jul 20 |

## AssemblyAI vs Soniox pricing: true cost at 3 usage tiers

Monthly bill from published per-minute rates, batch and streaming separately. Sticker rates only; diarization and PII redaction add-ons price in the stack builder.

| Volume | Buyer | AssemblyAI | Soniox | Note |
| --- | --- | --- | --- | --- |
| 1K min/mo (batch) | Side project | $3.50 | $1.67 | About 17 hours of audio. Free tiers may cover part of this. |
| 10K min/mo (batch) | Production app | $35 | $16.67 | About 167 hours of audio a month. |
| 100K min/mo (batch) | Call-center scale | $350 | $166.70 | About 1,667 hours. Most vendors negotiate volume rates here. |
| 1K min/mo (streaming) | Side project | $7.50 | $2 | About 17 hours of audio. Free tiers may cover part of this. |
| 10K min/mo (streaming) | Production app | $75 | $20 | About 167 hours of audio a month. |
| 100K min/mo (streaming) | Call-center scale | $750 | $200 | About 1,667 hours. Most vendors negotiate volume rates here. |

## AssemblyAI vs Soniox: verdicts by use case

### Dictation → Tie

The available facts cover API-level attributes such as batch pricing, streaming latency, WER, diarization, and compliance, but none address the attributes that decide the dictation use case: platform support for voice typing apps, local versus cloud audio processing, AI formatting and editing features, one-time versus subscription app pricing, or app integrations. Without any facts on these heavily weighted attributes for either AssemblyAI or Soniox, there is no basis to favor one tool over the other for this use case.

### Medical → AssemblyAI

Both tools offer a HIPAA BAA and SOC 2 Type II certification, making them equal on the two highest-weighted compliance requirements. The differentiator falls on PII redaction: AssemblyAI offers it as a paid add-on at about $0.08 per hour, while Soniox does not offer PII redaction at all. For clinical transcription under US healthcare privacy law, the ability to automatically redact protected health information from transcripts is a meaningful capability advantage. Both tools support custom vocabulary for medical terminology. On self-hosting, AssemblyAI supports on-premises deployment while Soniox does not, giving AssemblyAI an additional edge on the second-lowest-weighted attribute. These two advantages together push AssemblyAI ahead in a use case where data handling controls are critical.

### Meetings → AssemblyAI

For recorded meetings and interviews, speaker diarization and summarization carry the most weight. AssemblyAI includes both: diarization is available as a paid add-on at about $0.02/hr, and a summarization endpoint is fully supported. Soniox includes diarization at no extra charge but offers no summarization capability at all, which is a decisive gap at a weight of 4/5. On language coverage, AssemblyAI supports 99 languages versus 60 for Soniox. For long-file handling, AssemblyAI accepts files up to 5 GB and 10 hours, while Soniox caps files at 300 minutes. Word-level timestamps are equal. Soniox wins on per-minute pricing, but cost is not among the weighted attributes here. AssemblyAI leads on the top two attributes and also on file size handling and language breadth.

### Self-Hosted → AssemblyAI

For a self-hosted deployment, the single most critical factor is whether a vendor actually offers a self-host or on-prem option. AssemblyAI explicitly supports self-hosting, while Soniox offers no self-host or on-prem option at all. This alone is decisive given the 5/5 weight on that attribute. Neither tool publishes facts on open weights licensing, hardware requirements, maintenance status, or model parameter counts, so those attributes cannot differentiate the two. Because Soniox cannot be self-hosted at all, it cannot serve this use case in any meaningful way.

### Voice Agents → AssemblyAI

For voice agents, streaming latency is the top-weighted factor. AssemblyAI claims 150 ms latency versus Soniox at 249 ms, a meaningful gap when the goal is natural turn-taking in a live conversation. Both tools provide a WebSocket streaming API, so that is a wash. On streaming price, AssemblyAI charges $0.0075 per audio minute versus Soniox at $0.002, making Soniox cheaper on that dimension. However, concurrency swings back to AssemblyAI: it supports 100 new streams per minute on the base plan compared to Soniox's 10 concurrent WebSocket sessions, which matters when scaling a voice bot fleet. Both offer custom vocabulary boosting. The latency and concurrency advantages together outweigh Soniox's pricing edge.

## AssemblyAI vs Soniox: common questions

### Is AssemblyAI cheaper than Soniox?

On published per-minute rates, Soniox is cheaper than AssemblyAI. For batch transcription, Soniox charges about $0.0017/min versus AssemblyAI's $0.0035/min. For streaming, Soniox charges about $0.002/min versus AssemblyAI's $0.0075/min. Speaker diarization is included with Soniox but carries a small extra per-minute fee with AssemblyAI, so your total bill depends on which features you use. Both tools offer volume discounts through sales.

### AssemblyAI vs Soniox: which is better for call centers?

For call centers, the two services differ on several key points. AssemblyAI supports 99 languages versus Soniox's 60, and offers entity detection, sentiment analysis, and summarization, all of which are absent in Soniox. It also provides a self-host option for strict data environments. Soniox includes speaker diarization in its base price, while AssemblyAI charges a small extra per-minute cost for it. Soniox's batch and streaming rates are lower overall. The better fit depends on whether feature depth or a lower per-minute cost is the priority.

### Does AssemblyAI or Soniox offer a free trial to test before paying?

AssemblyAI gives new signups a $50 one-time credit with no credit card required. Soniox discontinued its free credits as of October 2025 and no longer offers a free tier. If trying the API without upfront commitment matters to you, AssemblyAI currently has the advantage.

### Is AssemblyAI or Soniox better for high-volume streaming workloads that need lots of concurrent sessions?

AssemblyAI supports 100 new streams per minute on its base plan and can grant higher limits at no additional cost. Soniox limits you to 10 concurrent WebSocket sessions and 100 requests per minute on its base plan. For workloads requiring high concurrency out of the box, AssemblyAI has a notable edge.

### Does AssemblyAI or Soniox include speaker diarization in the base price?

Soniox includes speaker diarization at no extra charge. AssemblyAI offers diarization as a paid add-on priced at about $0.0003 per audio minute, which adds up to roughly $0.02 per hour. If diarization is a core requirement and budget is tight, Soniox holds the pricing advantage for that specific feature.

### Which has better transcription accuracy: AssemblyAI or Soniox?

On a third-party benchmark, AssemblyAI scored a 3.02% word error rate while Soniox scored 3.81%, putting AssemblyAI slightly ahead in that test. Both vendors also publish self-reported figures, which differ. For the most reliable comparison, run both on your own audio data.

### Is AssemblyAI or Soniox better for building HIPAA-compliant healthcare applications?

Both AssemblyAI and Soniox offer a HIPAA BAA, SOC 2 Type II certification, and GDPR support. AssemblyAI additionally offers a self-hosted or on-premises deployment option, which Soniox does not. Teams with strict data-residency or air-gapped requirements may prefer AssemblyAI.

### Does AssemblyAI support more languages than Soniox?

AssemblyAI supports 99 languages while Soniox supports 60. Both platforms offer automatic language detection. If your application handles a wide variety of languages, AssemblyAI covers a broader range.

### Which tool offers more built-in audio intelligence features like sentiment analysis or summarization?

AssemblyAI offers entity detection, sentiment analysis, summarization, and 13 priced audio-intelligence add-ons in total. Soniox does not currently offer entity detection, sentiment analysis, or summarization. If your product needs downstream language understanding beyond transcription, AssemblyAI is the fuller-featured option.

### Does AssemblyAI or Soniox have lower claimed streaming latency?

AssemblyAI claims a streaming latency of 150 ms, while Soniox claims 249 ms. Both figures are vendor-reported and should be validated against your own use case. For latency-sensitive real-time applications, AssemblyAI's published number is lower, though independent verification is recommended.

Source: https://www.versusref.com/stt/assemblyai-vs-soniox/