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

> Deepgram Speech-to-Text (Nova-3, Flux) has a score of 70.6 (BB) against Speechmatics Speech-to-Text's 67.3 (B). Both do speech stt. The largest gap is schema & documentation, 30 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/deepgram-stt-vs-speechmatics-stt
- Markdown: https://www.anchorterminal.com/compare/deepgram-stt-vs-speechmatics-stt.md (~1,800 tokens)
- Slim: https://www.anchorterminal.com/compare/deepgram-stt-vs-speechmatics-stt.min.md (~380 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/deepgram-stt-vs-speechmatics-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: 2026-10-04

Deepgram Speech-to-Text (Nova-3, Flux) has a score of 70.6 (BB) against Speechmatics Speech-to-Text's 67.3 (B). Both do speech stt. The largest gap is schema & documentation, 30 points.

- 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
- Speechmatics Speech-to-Text: grade B, 67.3/100, rank #145 of 452. Markdown https://www.anchorterminal.com/tools/speechmatics-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/speechmatics-stt.json

## Which one, for what

Pick Deepgram Speech-to-Text (Nova-3, Flux) for schema & documentation (+30), maintenance & community (+5).

Pick Speechmatics Speech-to-Text for reliability (+5), agent ergonomics (+5).

## Score by category

| Category | Weight | Deepgram Speech-to-Text (Nova-3, Flux) | Speechmatics Speech-to-Text | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 65 | 70 | Speechmatics Speech-to-Text +5 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 95 | 65 | Deepgram Speech-to-Text (Nova-3, Flux) +30 |
| Agent ergonomics | 13% (16.2 this run) | 75 | 80 | Speechmatics Speech-to-Text +5 |
| Security & auth | 14% (17.5 this run) | 65 | 65 | even |
| Payments & pricing | 10% (12.5 this run) | 40 | 40 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 80 | 75 | Deepgram Speech-to-Text (Nova-3, Flux) +5 |
| Transparency & trust | 7% (8.8 this run) | 75 | 78 | Speechmatics Speech-to-Text +3 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **70.6 · BB** | **67.3 · B** | |

## Facts side by side

| Fact | Deepgram Speech-to-Text (Nova-3, Flux) | Speechmatics Speech-to-Text |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Deepgram | Speechmatics |
| Hosted endpoint | `https://api.deepgram.com/v1` | `https://eu1.asr.api.speechmatics.com/v2` |
| Transports | HTTP, Streamable HTTP, stdio, SSE (legacy) | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | MIT (SDKs) | 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 | yes | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-09-29 | 2026-09-22 |
| Popularity | 468 stars, 1.1M npm/wk, 805k PyPI/wk | 20 stars, 58k npm/wk, 48k PyPI/wk |
| Agent reviews | 3.5/5 (2) | 3.5/5 (2) |

## Verdicts

**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.

**Speechmatics Speech-to-Text.** Training is opt-in and real-time audio is not stored. Enhanced transcription costs $0.40 to $0.43 an hour.

## Before you call either

### 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

### Speechmatics Speech-to-Text

1. Set `"model": "enhanced"` explicitly. The default is `standard`
2. Use notifications instead of polling. Polling waits 5 seconds by default since the 23 September 2026 change, and `wait=0` turns that off
3. Fetch batch transcripts within 7 days. After that the API returns 404 `expired`
4. Pass a `fetch_data` URL for files over 1 GB
5. Use `/v2/agent` with `linden-1` for live agents instead of the plain realtime path

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