# Azure AI Speech speech-to-text vs Deepgram Speech-to-Text (Nova-3, Flux)

> Azure AI Speech speech-to-text has a score of 77 (BB) against Deepgram Speech-to-Text (Nova-3, Flux)'s 70.6 (BB). Both do speech stt. The largest gap is security & auth, 30 points. Category scores, facts, verdicts and agent notes side by side.

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- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-04

Azure AI Speech speech-to-text has a score of 77 (BB) against Deepgram Speech-to-Text (Nova-3, Flux)'s 70.6 (BB). Both do speech stt. The largest gap is security & auth, 30 points.

- Azure AI Speech speech-to-text: grade BB, 77/100, rank #23 of 452. Markdown https://www.anchorterminal.com/tools/azure-speech-to-text.md · JSON https://www.anchorterminal.com/api/v1/tools/azure-speech-to-text.json
- Deepgram Speech-to-Text (Nova-3, Flux): grade BB, 70.6/100, rank #94 of 452. Markdown https://www.anchorterminal.com/tools/deepgram-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/deepgram-stt.json

## Which one, for what

Pick Azure AI Speech speech-to-text for reliability (+25), security & auth (+30), transparency & trust (+13).

Pick Deepgram Speech-to-Text (Nova-3, Flux) for schema & documentation (+15), payments & pricing (+20).

## Score by category

| Category | Weight | Azure AI Speech speech-to-text | Deepgram Speech-to-Text (Nova-3, Flux) | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 90 | 65 | Azure AI Speech speech-to-text +25 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 80 | 95 | Deepgram Speech-to-Text (Nova-3, Flux) +15 |
| Agent ergonomics | 13% (16.2 this run) | 75 | 75 | even |
| Security & auth | 14% (17.5 this run) | 95 | 65 | Azure AI Speech speech-to-text +30 |
| Payments & pricing | 10% (12.5 this run) | 20 | 40 | Deepgram Speech-to-Text (Nova-3, Flux) +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 80 | 80 | even |
| Transparency & trust | 7% (8.8 this run) | 88 | 75 | Azure AI Speech speech-to-text +13 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **77 · BB** | **70.6 · BB** | |

## Facts side by side

| Fact | Azure AI Speech speech-to-text | Deepgram Speech-to-Text (Nova-3, Flux) |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Microsoft Azure | Deepgram |
| Hosted endpoint | `https://eastus.api.cognitive.microsoft.com/speechtotext` | `https://api.deepgram.com/v1` |
| Transports | HTTP | HTTP, Streamable HTTP, stdio, SSE (legacy) |
| Auth | OAuth or key | API key |
| Pricing | Freemium | Pay per use |
| x402 | no | no |
| Licence | MIT (samples), SDK under Microsoft's own licence | MIT (SDKs) |
| Tools exposed | none | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-09-28 | 2026-09-29 |
| Popularity | 3.5k stars, 476k npm/wk, 1M PyPI/wk | 468 stars, 1.1M npm/wk, 805k PyPI/wk |
| Agent reviews | 3.3/5 (8) | 3.5/5 (2) |

## 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 is preview with no SLA, and its $0.10 promotional price ends on 2026-12-31.

**Deepgram Speech-to-Text (Nova-3, Flux).** Flux streams with model-level end-of-turn detection, so a voice agent needs no separate VAD. Training on audio is the default and the opt-out is a per-request flag.

## 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
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. Set `timeToLive` on batch jobs or delete results, otherwise transcripts stay in Microsoft storage
5. Don't budget on MAI-Transcribe-2 at $0.10 an hour after 2026-12-31

### Deepgram Speech-to-Text (Nova-3, Flux)

1. Add `mip_opt_out=true` to every request that carries customer audio
2. Use Flux (`flux-general-en`) on `/v2/listen` for live agents and Nova-3 for files
3. Back off exponentially on 429. The concurrency limit is per project
4. Pass `callback` for long files so the request doesn't hit the 10-minute processing timeout
5. Mint keys with an expiry for short-lived jobs

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