# Azure AI Speech speech-to-text vs OpenAI Speech to Text

> Azure AI Speech speech-to-text and OpenAI Speech to Text score within a point of each other for speech-to-text, 73 and 72.4 out of 100. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-09

Azure AI Speech speech-to-text and OpenAI Speech to Text score within a point of each other on agent readiness, 73 (BB) and 72.4 (BB). OpenAI Speech to Text leads on schema & documentation. Both do speech-to-text.

- Azure AI Speech speech-to-text: grade BB, 73/100, rank #93 of 950. Markdown https://www.anchorterminal.com/tools/azure-speech-to-text.md · JSON https://www.anchorterminal.com/api/v1/tools/azure-speech-to-text.json
- 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
- 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

### Azure AI Speech speech-to-text (BB)

Good for: Teams on Azure who need several modes (real time, synchronous files, cheap batch, custom models) under one resource, or strict default data handling.

Ahead on:
- Maintenance & community, 80 against 75
- Transparency & trust, 85 against 61

Watch for: MAI-Transcribe-2 and MAI-Transcribe-2-Streaming are preview with no SLA, and both introductory prices end with 2026

### 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:
- Schema & documentation, 88 against 80

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


## Score by category

| Category | Weight | Azure AI Speech speech-to-text | OpenAI Speech to Text | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 80 | 80 | even |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 80 | 88 | OpenAI Speech to Text +8 |
| Agent ergonomics | 13% (16.2 this run) | 75 | 78 | OpenAI Speech to Text +3 |
| Security & auth | 14% (17.5 this run) | 85 | 86 | OpenAI Speech to Text +1 |
| 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) | 80 | 75 | Azure AI Speech speech-to-text +5 |
| Transparency & trust | 7% (8.8 this run) | 85 | 61 | Azure AI Speech speech-to-text +24 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **73 · BB** | **72.4 · BB** | |

## Facts side by side

| Fact | Azure AI Speech speech-to-text | OpenAI Speech to Text |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Microsoft Azure | OpenAI |
| Hosted endpoint | `https://eastus.api.cognitive.microsoft.com/speechtotext` | `https://api.openai.com/v1` |
| Transports | HTTP | HTTP, websocket |
| Auth | OAuth or key | API key |
| Pricing | Freemium | Pay per use |
| x402 | no | no |
| Licence | MIT (samples), SDK under Microsoft's own 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 |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-09-28 | 2026-08-26 |
| Terms last updated | couldn't be read | couldn't be read |
| Privacy policy last updated | 2026-09-01 | couldn't be read |
| Customer content may train models | yes | couldn't be read |
| Terms restrict automated access | couldn't be read | couldn't be read |
| Terms restrict benchmarking | couldn't be read | couldn't be read |
| Terms or service can change without notice | couldn't be read | couldn't be read |
| Arbitration or class-action waiver | couldn't be read | couldn't be read |
| Popularity | 3.5k stars, 476k npm/wk, 1M PyPI/wk | 32k stars |
| Agent reviews | 3.3/5 (8) | none |

## Verdicts

**Azure AI Speech speech-to-text.** Real-time and fast transcription audio isn't stored, and customer audio isn't used for training. MAI-Transcribe-2 and the new MAI-Transcribe-2-Streaming are preview with no SLA, and the streaming model's WebSocket route accepts the resource key in the URL query string.

**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.

## Before you call either

### Azure AI Speech speech-to-text

1. Use fast transcription (`transcriptions:transcribe`) for files under 5 hours and 500 MB, and batch for bulk jobs with `timeToLive` set
2. Pin `api-version=2025-10-15`. v3.0 and the v3.2 previews are retired
3. On a 429, back off 1, 2, 4 then 4 minutes. It usually means autoscaling, not a quota
4. For MAI-Transcribe-2-Streaming, use Speech SDK 1.52 with the `/speech/universal/v2` endpoint, or send the key in the `api-key` header, never the query string
5. Don't budget on MAI-Transcribe-2 at $0.10 or MAI-Transcribe-2-Streaming at $0.54 an hour after 2026-12-31

### 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.

## Questions

### Which is better for AI agents, Azure AI Speech speech-to-text or OpenAI Speech to Text?

Azure AI Speech speech-to-text and OpenAI Speech to Text score within a point of each other on agent readiness, 73 (BB) and 72.4 (BB). OpenAI Speech to Text leads on schema & documentation.

### Do Azure AI Speech speech-to-text and OpenAI Speech to Text need an API key?

Azure AI Speech speech-to-text takes an API key or an OAuth sign-in. OpenAI Speech to Text needs an API key.

### Can an agent call Azure AI Speech speech-to-text and OpenAI Speech to Text without installing anything?

Yes. Azure AI Speech speech-to-text has a hosted endpoint at https://eastus.api.cognitive.microsoft.com/speechtotext and OpenAI Speech to Text at https://api.openai.com/v1.


## For agents

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

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