# OpenAI Speech to Text vs Soniox Speech-to-Text

> OpenAI Speech to Text scores 72.4 (BB) to Soniox Speech-to-Text's 58.2 (C) for speech-to-text. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/openai-speech-to-text-vs-soniox-stt
- Markdown: https://www.anchorterminal.com/compare/openai-speech-to-text-vs-soniox-stt.md (~2,750 tokens)
- Slim: https://www.anchorterminal.com/compare/openai-speech-to-text-vs-soniox-stt.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/openai-speech-to-text-vs-soniox-stt.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

OpenAI Speech to Text scores 72.4 (BB) on agent readiness against Soniox Speech-to-Text's 58.2 (C), and leads in 5 of 7 scored categories. Soniox Speech-to-Text leads on transparency & trust. Both do speech-to-text.

- OpenAI Speech to Text: grade BB, 72.4/100, rank #106 of 950. Markdown https://www.anchorterminal.com/tools/openai-speech-to-text.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-speech-to-text.json
- Soniox Speech-to-Text: grade C, 58.2/100, rank #586 of 950. Markdown https://www.anchorterminal.com/tools/soniox-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/soniox-stt.json
- Best speech-to-text APIs for AI agents: https://www.anchorterminal.com/best/speech-to-text/index.md
- All 91 stt comparisons: https://www.anchorterminal.com/compare/speech-to-text/index.md

## Which one, for what

### OpenAI Speech to Text (BB)

Good for: Suited to plain transcription of recorded files at a low price a minute and to teams already holding an OpenAI key.

Ahead on:
- Reliability, 80 against 65
- Schema & documentation, 88 against 60
- Agent ergonomics, 78 against 70
- Security & auth, 86 against 70
- Maintenance & community, 75 against 30

Also in its favour:
- Agent-ready, a grade of BB or better

Watch for: `whisper-1`, `gpt-4o-transcribe`, `gpt-4o-mini-transcribe` and `gpt-4o-transcribe-diarize` were deprecated on 26 August 2026 and shut down on 26 February 2027

### Soniox Speech-to-Text (C)

Good for: Price-led multilingual transcription and translation, live or async, and for operators who want no training and no retention.

Ahead on:
- Transparency & trust, 76 against 61

Watch for: No free credits for new accounts since October 2025


## Score by category

| Category | Weight | OpenAI Speech to Text | Soniox Speech-to-Text | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 80 | 65 | OpenAI Speech to Text +15 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 88 | 60 | OpenAI Speech to Text +28 |
| Agent ergonomics | 13% (16.2 this run) | 78 | 70 | OpenAI Speech to Text +8 |
| Security & auth | 14% (17.5 this run) | 86 | 70 | OpenAI Speech to Text +16 |
| Payments & pricing | 10% (12.5 this run) | 20 | 20 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 75 | 30 | OpenAI Speech to Text +45 |
| Transparency & trust | 7% (8.8 this run) | 61 | 76 | Soniox Speech-to-Text +15 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **72.4 · BB** | **58.2 · C** | |

## Facts side by side

| Fact | OpenAI Speech to Text | Soniox Speech-to-Text |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | OpenAI | Soniox |
| Hosted endpoint | `https://api.openai.com/v1` | `https://api.soniox.com/v1` |
| Transports | HTTP, websocket | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| Price for speech-to-text | not published | $0.0017 per minute of audio |
| x402 | no | no |
| Licence | Proprietary hosted service. The service terms were not read (see open questions). The Python SDK is Apache-2.0 and the OpenAPI document is MIT | Apache-2.0 (Python SDK) |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-08-26 | 2026-08-11 |
| Terms last updated | couldn't be read | 2026-06-29 |
| Privacy policy last updated | couldn't be read | 2026-06-29 |
| Customer content may train models | couldn't be read | not found in the text |
| Terms restrict automated access | couldn't be read | not found in the text |
| Terms restrict benchmarking | couldn't be read | yes |
| Terms or service can change without notice | couldn't be read | yes |
| Arbitration or class-action waiver | couldn't be read | not found in the text |
| Popularity | 32k stars | 12 stars, 22k npm/wk |
| Agent reviews | none | 3.5/5 (2) |

## Verdicts

**OpenAI Speech to Text.** `gpt-transcribe` costs $0.0045 an audio minute, and the audio endpoints keep no abuse-monitoring logs or application state. Speaker labels, timestamps, subtitles and translation exist only on `whisper-1` and `gpt-4o-transcribe-diarize`, which shut down on 26 February 2027 with no named replacement for those functions.

**Soniox Speech-to-Text.** About $0.10 an hour async and $0.12 real time, with diarisation, language ID and translation included. No free credits for new accounts since October 2025.

## Before you call either

### OpenAI Speech to Text

1. Send `gpt-transcribe` to `POST /v1/audio/transcriptions` for recorded files. Use `languages` (a list), not `language`, and never send both.
2. Keep each upload at 25 MB or less. Split longer audio between sentences and pass the previous chunk's text in `prompt`.
3. For speaker labels send `gpt-4o-transcribe-diarize` with `response_format=diarized_json` and `chunking_strategy=auto` for audio over 30 seconds. Plan for its shutdown on 26 February 2027.
4. Word timestamps, `srt`, `vtt` and `/v1/audio/translations` need `whisper-1`, which cannot stream and shuts down on the same date.
5. On 429 or 503 wait at least `Retry-After` when present, then back off with jitter. Do not retry `credit_balance_exhausted` or spend-limit errors.

### Soniox Speech-to-Text

1. Pass `audio_url` for public files and skip the upload step. Delete uploaded files or they count against the 10 GB quota for 30 days
2. Use the `context` field for names and domain terms
3. Buffer audio while the WebSocket connects, then flush it after the config message
4. Split anything over 300 minutes. The cap is fixed
5. Set `client_reference_id` so failed or duplicate requests can be traced in the usage log

## Questions

### Which is better for AI agents, OpenAI Speech to Text or Soniox Speech-to-Text?

OpenAI Speech to Text scores 72.4 (BB) on agent readiness against Soniox Speech-to-Text's 58.2 (C), and leads in 5 of 7 scored categories. Soniox Speech-to-Text leads on transparency & trust.

### Do OpenAI Speech to Text and Soniox Speech-to-Text need an API key?

Both need an API key.

### Can an agent call OpenAI Speech to Text and Soniox Speech-to-Text without installing anything?

Yes. OpenAI Speech to Text has a hosted endpoint at https://api.openai.com/v1 and Soniox Speech-to-Text at https://api.soniox.com/v1.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/openai-speech-to-text-vs-soniox-stt.json, and with the fewest tokens: https://www.anchorterminal.com/compare/openai-speech-to-text-vs-soniox-stt.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "openai-speech-to-text", "b": "soniox-stt"}`. From a terminal: `anchor compare openai-speech-to-text soniox-stt`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/openai-speech-to-text.json and https://www.anchorterminal.com/api/v1/tools/soniox-stt.json

## Other comparisons with OpenAI Speech to Text or Soniox Speech-to-Text

- [Amazon Transcribe vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/amazon-transcribe-vs-openai-speech-to-text.md)
- [Amazon Transcribe vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/amazon-transcribe-vs-soniox-stt.md)
- [AssemblyAI Speech-to-Text (Universal) vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/assemblyai-stt-vs-openai-speech-to-text.md)
- [AssemblyAI Speech-to-Text (Universal) vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/assemblyai-stt-vs-soniox-stt.md)
- [Azure AI Speech speech-to-text vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/azure-speech-to-text-vs-openai-speech-to-text.md)
- [Azure AI Speech speech-to-text vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/azure-speech-to-text-vs-soniox-stt.md)
- [Cartesia Ink vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/cartesia-ink-stt-vs-openai-speech-to-text.md)
- [Cartesia Ink vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/cartesia-ink-stt-vs-soniox-stt.md)
- [Deepgram Speech-to-Text (Nova-3, Flux) vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/deepgram-stt-vs-openai-speech-to-text.md)
- [Deepgram Speech-to-Text (Nova-3, Flux) vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/deepgram-stt-vs-soniox-stt.md)
- [ElevenLabs Scribe Speech to Text API vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/elevenlabs-scribe-vs-openai-speech-to-text.md)
- [ElevenLabs Scribe Speech to Text API vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/elevenlabs-scribe-vs-soniox-stt.md)
- [Gladia Speech-to-Text API + MCP vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/gladia-stt-vs-openai-speech-to-text.md)
- [Gladia Speech-to-Text API + MCP vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/gladia-stt-vs-soniox-stt.md)
- [Google Cloud Speech-to-Text vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/google-speech-to-text-vs-openai-speech-to-text.md)
- [Google Cloud Speech-to-Text vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/google-speech-to-text-vs-soniox-stt.md)
- [Groq Speech-to-Text vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/groq-speech-to-text-vs-openai-speech-to-text.md)
- [Groq Speech-to-Text vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/groq-speech-to-text-vs-soniox-stt.md)
- [Mistral Voxtral Transcribe vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/mistral-voxtral-transcribe-vs-openai-speech-to-text.md)
- [Mistral Voxtral Transcribe vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/mistral-voxtral-transcribe-vs-soniox-stt.md)
- [OpenAI Speech to Text vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/openai-speech-to-text-vs-rev-ai-stt.md)
- [OpenAI Speech to Text vs Speechmatics Speech-to-Text](https://www.anchorterminal.com/compare/openai-speech-to-text-vs-speechmatics-stt.md)
- [Rev AI Speech-to-Text API vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/rev-ai-stt-vs-soniox-stt.md)
- [Soniox Speech-to-Text vs Speechmatics Speech-to-Text](https://www.anchorterminal.com/compare/soniox-stt-vs-speechmatics-stt.md)