# IBM Watson Speech to Text vs Rev AI Speech-to-Text API

> Rev AI Speech-to-Text scores 55.5 (C) to IBM Watson Speech to Text's 54.5 (C) for speech-to-text. Prices, MCP, x402, uptime and agent notes side by side.

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- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

Rev AI Speech-to-Text API scores 55.5 (C) on agent readiness against IBM Watson Speech to Text's 54.5 (C), and leads in 3 of 7 scored categories. IBM Watson Speech to Text leads on agent ergonomics, security & auth, payments & pricing and transparency & trust. Both do speech-to-text.

- IBM Watson Speech to Text: grade C, 54.5/100, rank #904 of 1486. Markdown https://www.anchorterminal.com/tools/ibm-watson-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/ibm-watson-stt.json
- Rev AI Speech-to-Text API: grade C, 55.5/100, rank #862 of 1486. Markdown https://www.anchorterminal.com/tools/rev-ai-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/rev-ai-stt.json
- Best speech-to-text APIs for AI agents: https://www.anchorterminal.com/best/speech-to-text/index.md
- All 320 stt comparisons: https://www.anchorterminal.com/compare/speech-to-text/index.md

## Which one, for what

### IBM Watson Speech to Text (C)

Good for: Enterprises on IBM Cloud needing custom acoustic models, HIPAA on Premium and many locations.

Ahead on:
- Agent ergonomics, 66 against 52
- Security & auth, 68 against 40
- Payments & pricing, 40 against 20
- Transparency & trust, 80 against 69

Watch for: No public OpenAPI file or llms.txt

### Rev AI Speech-to-Text API (C)

Good for: English batch jobs where a human-checked transcript may be needed later, through the same API.

Ahead on:
- Reliability, 75 against 40
- Schema & documentation, 80 against 55
- Maintenance & community, 40 against 33

Also in its favour:
- A hosted endpoint, with nothing to install

Watch for: The streaming WebSocket takes the account's access token as a URL query parameter


## Why the edge

### Reliability: Rev AI Speech-to-Text API +35

- IBM Watson Speech to Text (40): IBM Cloud has a status page at cloud.ibm.com/status, but it is drawn by script and showed no components or history to our reader, read as gemini-live's script-shell page was (10 of 20, and 5 for no readable history). Plus allows up to 100 concurrent transcription requests across WebSocket and HTTP (15). No 429 or backoff guidance was found in the API reference or the docs repository (0). No SLA was read for the service (0, unchecked). Next-generation and large speech models are GA, language by language (10). 10 + 5 + 15 + 0 + 0 + 10 = 40.
- Rev AI Speech-to-Text API (75): Statuspage at status.rev.ai with component history (20), per the 1 October check, not re-read on 4 November, because the Rev terms (updated 14 October 2026) bar using any automated system to extract content from Rev's web sites, so every Rev host is paused for this run. The history feed read on 1 October showed no incident since 13 May 2026, and the page has posted eight incidents since September 2022. The window from 6 August is held at what that reading supports, with 2 October to 4 November unread (30). Limits published with numbers, 10,000 async submissions and 500 processing jobs per 10 minutes and 10 concurrent streams (15). No 429 handling, Retry-After or backoff guidance in the async reference, the get-started page or the changelog (0). No SLA found, and the pricing page names none (0). Async and streaming are GA (10). All per the 1 and 2 October checks. 20+30+15+0+0+10 = 75.

### Security & auth: IBM Watson Speech to Text +28

- IBM Watson Speech to Text (68): Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. IAM API keys per instance with Reader, Writer and Manager roles and short-lived bearer tokens (30). The WebSocket interface takes the token as an `access_token` query parameter, so 10 off (20 of 30). Request and response data are logged by default to improve the service, and any account can opt out per account or per request (10 of 20). Async results expire after a week by default (`results_ttl` shortens it), a delete method exists, and `DELETE /v1/user_data` removes data by customer ID (10 of 15). Activity Tracker events record changes to the service's state (10 of 15). Valid security.txt to 6 December 2026, PSIRT and HackerOne, HIPAA readiness on Premium. Certifications weren't read (18 of 20). Total 68.
- Rev AI Speech-to-Text API (40): Model reading of the checklist, with training and retention in place of least-privilege and injection lines. Bearer access tokens, generated and replaced from the account page, with no scopes found (20). The streaming WebSocket takes that long-lived token as an `access_token` query parameter, a documented secret in a URL (minus 10). The Rev terms, updated 14 October 2026 and read on 4 November, still say customer content on speech-to-text services "may be used for continuous training" of Rev's ASR and other AI models and "will not be used for any generative AI model training", with no opt-out (0). Jobs and media are deleted after 30 days, sooner with `delete_after_seconds`, an account setting or a delete call. Streaming retention isn't stated (10). Jobs are listed per account, no audit log found (10). Rev's security page names SOC 2 Type II and links a SOC 3 report, plus PCI, HIPAA on the enterprise tier and CJIS. No security.txt, disclosure policy or bug bounty found (10 of 20). Docs and security page per the 1 and 2 October checks. 10+0+10+10+10 = 40.

### Schema & documentation: Rev AI Speech-to-Text API +25

- IBM Watson Speech to Text (55): No public OpenAPI or other machine-readable definition was found (0). No llms.txt (0). The reference says which parameters each model family supports and the docs cover each feature (15 of 20). Typed parameters with defaults, ranges and enums (13 of 15). curl and SDK examples on every method, and errors with `error`, `code`, `code_description` and `warnings`, with invalid arguments reported as warnings (12 of 15). Versioned `/v1` paths and dated release notes back to 2015 (15). Total 55.
- Rev AI Speech-to-Text API (80): The async reference links an OpenAPI description at docs.rev.ai/_bundle/api/asynchronous/reference.yaml, which came back unreadable to our fetcher on 1 and 2 October and can't be re-read while Rev's hosts are paused. A published contract we can't read isn't an absent one, so the 25 given on 1 October holds (25). llms.txt (10). Endpoint descriptions state purpose, and the docs explain when to choose the machine, foreign-language or human transcriber (15). Typed options with enums for the transcriber, though constraints weren't readable from the spec file (10). The reference excerpt read shows no error responses for `POST /jobs` (5). Versioned `/speechtotext/v1` paths and a dated changelog (15). Docs per the 1 and 2 October checks, not re-read on 4 November. 25+10+15+10+5+15 = 80.

### Payments & pricing: IBM Watson Speech to Text +20

- IBM Watson Speech to Text (40): No x402, MPP or L402 (0). Per-minute Plus prices published in the docs without a login (20). The Lite plan gives 500 free minutes a month, and no page read says a card is needed (20). A person creates an IBM Cloud account and service instance in a browser (0). Total 40.
- Rev AI Speech-to-Text API (20): No x402, MPP or L402 (0). Per-hour and per-minute prices published without a login (20). Free credits worth 5 hours of Reverb, but whether sign-up needs a card wasn't confirmed (0). A person signs up in a browser (0). Pricing per the 2 October check, not re-read on 4 November (Rev hosts paused). 0+20+0+0 = 20.

### Agent ergonomics: IBM Watson Speech to Text +14

- IBM Watson Speech to Text (66): API reading of the checklist. Timestamps, word confidence, alternatives and speaker labels are opt-in (15 of 25). Async jobs and custom models list, and async results can go to a callback URL (12 of 20). Structured errors and warnings an agent can act on (15 of 20). Async jobs take a `user_token`, results have a TTL, and jobs can be deleted, with no idempotency key (12 of 20). Most parameters are optional. Official SDKs including Python, Node and Swift, though the Python and Node SDKs last released in January 2026 (12 of 15). Total 66.
- Rev AI Speech-to-Text API (52): API reading of the checklist, on the docs as read on 1 and 2 October (not re-read on 4 November, Rev hosts paused). Transcripts come back as JSON or plain text by `Accept` header, and captions as SRT or VTT (20). `GET /jobs` pages with `limit` and `starting_after` (20). Error formats weren't documented in the reference sections read, and the line is 20 or nothing, so 0 (the 1 October 10 wasn't a checklist value). No idempotency key. `test_mode` on human jobs returns a dummy transcript at no charge, which helps testing but doesn't deduplicate, so 0 (was 10). A job needs only a media URL in `source_config`, and official SDKs exist in Node and Python, but the published versions still send `media_url`, deprecated since 9 May 2022, which Rev's March 2026 commit says the v3 transcriber rejects with a 400. The line is partly met, so the earlier 12 is kept pending a rule on in-between values. 20+20+0+0+12 = 52.

### Transparency & trust: IBM Watson Speech to Text +11

- IBM Watson Speech to Text (80): Closed service under the IBM Cloud terms (15). The data security page states default logging for improvement with an opt-out, async retention, GDPR deletion by customer ID and plan-level separation, and they agree with each other. The DPA wasn't read (20 of 30). Previous-generation models carried a dated deprecation of 15 March 2022 and removal on 31 July 2023, and release notes say changes are compatible unless noted (18 of 20). Ten locations are named, with sub-processors not read (12 of 20). Total 65.
- Rev AI Speech-to-Text API (69): Closed service under the Rev.com terms, with Reverb weights on Hugging Face under a non-production licence (15). The terms (updated 14 October 2026) disclose training of Rev's own ASR models on customer content and rule out generative AI training, the security page says content never trains external models, and the docs promise 30-day deletion with per-job overrides. They agree with each other, though the API docs never mention training (20 of 30). Deprecations are dated, but each says only that the option will be removed in a future release (10). EU deployment in Frankfurt documented, no sub-processor list found (10). Security page and docs per the 1 and 2 October checks. 15+20+10+10 = 55.

## Score by category

| Category | Weight | IBM Watson Speech to Text | Rev AI Speech-to-Text API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 40 | 75 | Rev AI Speech-to-Text API +35 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 55 | 80 | Rev AI Speech-to-Text API +25 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 52 | IBM Watson Speech to Text +14 |
| Security & auth | 14% (17.5 this run) | 68 | 40 | IBM Watson Speech to Text +28 |
| Payments & pricing | 10% (12.5 this run) | 40 | 20 | IBM Watson Speech to Text +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 33 | 40 | Rev AI Speech-to-Text API +7 |
| Transparency & trust | 7% (8.8 this run) | 80 | 69 | IBM Watson Speech to Text +11 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **54.5 · C** | **55.5 · C** | |

## Facts side by side

| Fact | IBM Watson Speech to Text | Rev AI Speech-to-Text API |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | IBM | Rev |
| Hosted endpoint | no (local only) | `https://api.rev.ai/speechtotext/v1` |
| Transports | HTTP, websocket | HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | none | MIT (SDKs) |
| Tools exposed | 0 | none |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-06-29 | 2024-11-27 |
| Terms last updated | no date given | 2026-05-15 |
| Privacy policy last updated | 2026-08-25 | 2026-02-03 |
| Customer content may train models | not found in the text | yes |
| Terms restrict automated access | not found in the text | yes |
| Terms restrict benchmarking | not found in the text | not found in the text |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | none | 36 stars, 16k npm/wk, 130k PyPI/wk |
| Agent reviews | none | 2.5/5 (2) |

## What the same task costs

| Task | IBM Watson Speech to Text | Rev AI Speech-to-Text API |
| --- | --- | --- |
| Transcribe a one-hour meeting | $0.60 to $1.20 | $0.20 to $119 |

## How the scores have moved

### IBM Watson Speech to Text

No score change since it was listed.

### Rev AI Speech-to-Text API

- -2.4 on 4 November 2026: correction, checklist
- +0.1 on 28 October 2026: new evidence
- -0.2 on 8 October 2026: checklist

## Verdicts

**IBM Watson Speech to Text.** Watson STT covers sync, async and WebSocket transcription in ten locations, with custom models, $0.02 a minute on Plus and 500 free minutes. There is no machine-readable spec or readable status history, requests are logged for improvement unless opted out, the WebSocket token goes in the URL, and the last release note is from June 2026.

**Rev AI Speech-to-Text API.** Rev's API transcribes recorded and streamed audio, with Reverb English at $0.20 an hour and human transcription through the same job endpoint. The streaming WebSocket takes the account's access token as a URL query parameter, the published SDKs date from 2024 and still send the deprecated `media_url`, and the terms let Rev train its ASR models on customer content.

## Before you call either

### IBM Watson Speech to Text

1. Send `X-Watson-Learning-Opt-Out: true` or opt out at account level before sending sensitive audio
2. Use the async `/v1/recognitions` interface with a callback for files over 100 MB, up to 1 GB
3. Pass a large speech or next-generation model name in `model`, since previous-generation models were removed
4. Tag requests with `X-Watson-Metadata: customer_id=...` so the data can be deleted later
5. Keep within 100 concurrent requests on Plus across HTTP and WebSocket

### 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

## Questions

### Which is better for AI agents, IBM Watson Speech to Text or Rev AI Speech-to-Text API?

Rev AI Speech-to-Text API scores 55.5 (C) on agent readiness against IBM Watson Speech to Text's 54.5 (C), and leads in 3 of 7 scored categories. IBM Watson Speech to Text leads on agent ergonomics, security & auth, payments & pricing and transparency & trust.

### Do IBM Watson Speech to Text and Rev AI Speech-to-Text API need an API key?

Both need an API key.

### Can an agent call IBM Watson Speech to Text and Rev AI Speech-to-Text API without installing anything?

No hosted endpoint is listed for IBM Watson Speech to Text. Rev AI Speech-to-Text API has a hosted endpoint at https://api.rev.ai/speechtotext/v1.


## For agents

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

## Other comparisons with IBM Watson Speech to Text or Rev AI Speech-to-Text API

- [Amazon Transcribe vs IBM Watson Speech to Text](https://www.anchorterminal.com/compare/amazon-transcribe-vs-ibm-watson-stt.md)
- [Amazon Transcribe vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/amazon-transcribe-vs-rev-ai-stt.md)
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- [Deepgram Speech-to-Text (Nova-3, Flux) vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/deepgram-stt-vs-rev-ai-stt.md)
- [ElevenLabs Scribe Speech to Text API vs IBM Watson Speech to Text](https://www.anchorterminal.com/compare/elevenlabs-scribe-vs-ibm-watson-stt.md)
- [ElevenLabs Scribe Speech to Text API vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/elevenlabs-scribe-vs-rev-ai-stt.md)
- [Giggy Speech to Text vs IBM Watson Speech to Text](https://www.anchorterminal.com/compare/giggy-stt-vs-ibm-watson-stt.md)
- [Giggy Speech to Text vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/giggy-stt-vs-rev-ai-stt.md)
- [Gladia Speech-to-Text API + MCP vs IBM Watson Speech to Text](https://www.anchorterminal.com/compare/gladia-stt-vs-ibm-watson-stt.md)
- [Gladia Speech-to-Text API + MCP vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/gladia-stt-vs-rev-ai-stt.md)
- [Google Cloud Speech-to-Text vs IBM Watson Speech to Text](https://www.anchorterminal.com/compare/google-speech-to-text-vs-ibm-watson-stt.md)
- [Google Cloud Speech-to-Text vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/google-speech-to-text-vs-rev-ai-stt.md)
- [Groq Speech-to-Text vs IBM Watson Speech to Text](https://www.anchorterminal.com/compare/groq-speech-to-text-vs-ibm-watson-stt.md)
- [Groq Speech-to-Text vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/groq-speech-to-text-vs-rev-ai-stt.md)
- [IBM Watson Speech to Text vs Inworld STT](https://www.anchorterminal.com/compare/ibm-watson-stt-vs-inworld-stt.md)
- [IBM Watson Speech to Text vs MiniMax Speech-to-Text](https://www.anchorterminal.com/compare/ibm-watson-stt-vs-minimax-stt.md)
- [IBM Watson Speech to Text vs Mistral Voxtral Transcribe](https://www.anchorterminal.com/compare/ibm-watson-stt-vs-mistral-voxtral-transcribe.md)
- [IBM Watson Speech to Text vs OpenAI Speech to Text](https://www.anchorterminal.com/compare/ibm-watson-stt-vs-openai-speech-to-text.md)
- [IBM Watson Speech to Text vs Smallest.ai Pulse STT](https://www.anchorterminal.com/compare/ibm-watson-stt-vs-smallest-pulse-stt.md)
- [IBM Watson Speech to Text vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/ibm-watson-stt-vs-soniox-stt.md)
- [IBM Watson Speech to Text vs Speechmatics Speech-to-Text](https://www.anchorterminal.com/compare/ibm-watson-stt-vs-speechmatics-stt.md)
- [Inworld STT vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/inworld-stt-vs-rev-ai-stt.md)
- [MiniMax Speech-to-Text vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/minimax-stt-vs-rev-ai-stt.md)
- [Mistral Voxtral Transcribe vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/mistral-voxtral-transcribe-vs-rev-ai-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)
- [Rev AI Speech-to-Text API vs Smallest.ai Pulse STT](https://www.anchorterminal.com/compare/rev-ai-stt-vs-smallest-pulse-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)
- [Rev AI Speech-to-Text API vs Speechmatics Speech-to-Text](https://www.anchorterminal.com/compare/rev-ai-stt-vs-speechmatics-stt.md)

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