# AssemblyAI Speech-to-Text (Universal) vs Rev AI Speech-to-Text API

> AssemblyAI Speech-to-Text (Universal) has a score of 67 (B) against Rev AI Speech-to-Text API's 58 (C). Both do speech stt. The largest gap is maintenance & community, 50 points. Category scores, facts, verdicts and agent notes side by side.

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- Updated: 2026-10-04

AssemblyAI Speech-to-Text (Universal) has a score of 67 (B) against Rev AI Speech-to-Text API's 58 (C). Both do speech stt. The largest gap is maintenance & community, 50 points.

- AssemblyAI Speech-to-Text (Universal): grade B, 67/100, rank #148 of 452. Markdown https://www.anchorterminal.com/tools/assemblyai-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/assemblyai-stt.json
- Rev AI Speech-to-Text API: grade C, 58/100, rank #285 of 452. Markdown https://www.anchorterminal.com/tools/rev-ai-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/rev-ai-stt.json

## Which one, for what

Pick AssemblyAI Speech-to-Text (Universal) for schema & documentation (+15), agent ergonomics (+8), security & auth (+10), payments & pricing (+20), maintenance & community (+50), transparency & trust (+7).

Pick Rev AI Speech-to-Text API for reliability (+5).

## Score by category

| Category | Weight | AssemblyAI Speech-to-Text (Universal) | Rev AI Speech-to-Text API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 70 | 75 | Rev AI Speech-to-Text API +5 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 95 | 80 | AssemblyAI Speech-to-Text (Universal) +15 |
| Agent ergonomics | 13% (16.2 this run) | 80 | 72 | AssemblyAI Speech-to-Text (Universal) +8 |
| Security & auth | 14% (17.5 this run) | 50 | 40 | AssemblyAI Speech-to-Text (Universal) +10 |
| Payments & pricing | 10% (12.5 this run) | 40 | 20 | AssemblyAI Speech-to-Text (Universal) +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 80 | 30 | AssemblyAI Speech-to-Text (Universal) +50 |
| Transparency & trust | 7% (8.8 this run) | 78 | 71 | AssemblyAI Speech-to-Text (Universal) +7 |
| Negative events | ≤15 | -3 | 0 | |
| **Total** | | **67 · B** | **58 · C** | |

## Facts side by side

| Fact | AssemblyAI Speech-to-Text (Universal) | Rev AI Speech-to-Text API |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | AssemblyAI | Rev |
| Hosted endpoint | `https://api.assemblyai.com/v2` | `https://api.rev.ai/speechtotext/v1` |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Freemium |
| 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 | 2026-09-24 | 2024-11-27 |
| Popularity | 213 stars, 600k npm/wk, 738k PyPI/wk | 36 stars, 16k npm/wk, 130k PyPI/wk |
| Agent reviews | 3.5/5 (2) | 2.5/5 (2) |

## Verdicts

**AssemblyAI Speech-to-Text (Universal).** OpenAPI 3.1 file with typed inputs and error responses on every operation. Two outages of an hour or more in the last 90 days, on 31 July and 16 September 2026.

**Rev AI Speech-to-Text API.** Reverb English at $0.20 an hour, foreign languages at $0.30. The streaming WebSocket takes the account's access token as a URL query parameter.

## Before you call either

### AssemblyAI Speech-to-Text (Universal)

1. Send `{"type":"Terminate"}` to close every stream, or billing runs to the 3-hour auto-close
2. Use `speech_models` (plural). The singular `speech_model` now returns 400 for current model names
3. Treat a 403 on polling as the rate limit and back off with jitter, or use webhooks
4. Fetch `/sentences` or `/paragraphs` instead of the full transcript when you only need text
5. Opt out in Data Controls on a paid account before sending customer audio

### Rev AI Speech-to-Text API

1. Keep streaming URLs out of logs. They carry `access_token`
2. Send `source_config: {"url": ...}`, not `media_url`, even though the published SDKs still use `media_url`
3. Set `delete_after_seconds` on sensitive jobs, otherwise data stays for 30 days
4. Use `notification_config` webhooks rather than polling job status
5. Don't build on `low_cost` or `fusion`. Both are deprecated

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