# IBM Watson Speech to Text vs Soniox Speech-to-Text

> Soniox Speech-to-Text scores 68.5 (B) 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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- Updated: 2026-11-07

Soniox Speech-to-Text scores 68.5 (B) on agent readiness against IBM Watson Speech to Text's 54.5 (C), and leads in 5 of 7 scored categories. IBM Watson Speech to Text leads on payments & pricing. Both do speech-to-text.

- IBM Watson Speech to Text: grade C, 54.5/100, rank #910 of 1510. Markdown https://www.anchorterminal.com/tools/ibm-watson-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/ibm-watson-stt.json
- Soniox Speech-to-Text: grade B, 68.5/100, rank #286 of 1510. Markdown https://www.anchorterminal.com/tools/soniox-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/soniox-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:
- Payments & pricing, 40 against 20

Also in its favour:
- No incidents deducted, where Soniox Speech-to-Text loses 3 points for them

Watch for: No public OpenAPI file or llms.txt

### Soniox Speech-to-Text (B)

Good for: Price-led multilingual transcription and translation, live or async, and for operators who want no training and no retention.

Ahead on:
- Reliability, 77 against 40
- Schema & documentation, 85 against 55
- Security & auth, 87 against 68
- Maintenance & community, 75 against 33

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

Watch for: No free credits for new accounts since October 2025


## Why the edge

### Maintenance & community: Soniox Speech-to-Text +42

- IBM Watson Speech to Text (33): Read as a model. The newest release note is 29 June 2026 (`parameter_set` for large speech models), 130 days ago (10). No dated entries in the 90 days from 8 August (0). Release notes, IBM support and a public docs repository last changed 30 June 2026 (8 of 15). Official SDKs, `ibm-watson` 11.2.0 on PyPI (26 January 2026) and 12.2.0 on npm (January 2026) (10 of 15). CI not read (5 of 10). Total 33.
- Soniox Speech-to-Text (75): Read on the model lines the other Soniox listings use (recency 30, dated releases 10, notice 10, support 15, issues 10, SDKs 15, health 10), where the 1 October note used the tool lines. `stt-rt-v6` and `stt-async-v6` released on 3 November 2026, with Python SDK 2.11.0 (agent text input on `RealtimeSTTConfig`) and soniox-js v2026.11.03 ("Feat/v6 support") the same day (30). Since 6 August, the releases that touch STT code are Python 2.9.0 (11 August, async STT and files), 2.10.0 (2 October, realtime STT authentication), 2.11.0, soniox-js v2026.10.12 (12 October, realtime STT authentication) and v2026.11.03, plus the v6 model entry (10). For notice, the v5 models are removed on 15 December 2026, 42 days after the notice, with requests routed to v6, and WebSocket `api_key` authentication ends on 15 January 2027 with a migration guide; v4 had 14 days (5). A community and support page, with no reply times read (5). SDK issues unread, github.com 403 (3). Current Python and Node SDKs (15). soniox-js runs CI (`.github/workflows/ci.yml`), the Python repository has tests and uv.lock but no CI workflow (7). 30+10+5+5+3+15+7 = 75.

### Reliability: Soniox Speech-to-Text +37

- 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.
- Soniox Speech-to-Text (77): Instatus page at status.soniox.com with per-region components and a paged history (20). Minor incidents only since 6 August, with 70 minutes of failed API key creation in the console on 24 August, failed new WebSocket connections to stt-rt.eu.soniox.com between 12:50 and 13:03 UTC on 25 August (existing connections unaffected), and 45 minutes of real-time overload in the Japan region on 8 September ("some customers", partial). October and November have no notices (20). Limits published with numbers, 100 requests a minute, 10 concurrent streams, a connection limit derived from them and a fixed 300-minute stream cap (15). The errors reference documents `limit_exceeded` as HTTP 429 on REST and the STT WebSocket with what to do for each limit, "retry with exponential backoff" for 503 `service_unavailable`, and resubmitting failed async jobs, which aren't auto-retried. No idempotency key, so safe-retry guidance without one (12), as soniox-tts. No SLA found (0). `stt-rt-v6` and `stt-async-v6` are active and the v5 models deprecated, with no preview label (10). 20+20+15+12+0+10 = 77.

### Schema & documentation: Soniox Speech-to-Text +30

- 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.
- Soniox Speech-to-Text (85): docs.soniox.com/openapi.yaml, OpenAPI 3.1.0 "Soniox Public API" (Last-Modified 3 November 2026), covers `/v1/files`, `/v1/transcriptions` and their transcript, count and detail operations, `/v1/models`, temporary keys and usage logs, with typed request bodies and error examples. No AsyncAPI file for the WebSocket (25). llms.txt with Markdown pages (10). Guides state purpose and say when to use the real-time or async API (15). Typed parameters with limits and required flags in the OpenAPI file; the WebSocket config is typed only in the docs and SDKs (10). Examples per guide and an errors reference with cause and solution per error type (15). Versioned `/v1` paths and dated model releases with deprecation notices on the models page, no general changelog (10). 25+10+15+10+15+10 = 85.

### 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.
- Soniox Speech-to-Text (20): No x402, MPP or L402 (0). Token prices published without a login, with Soniox's own per-hour estimates (20). No free credits for new sign-ups since 2025-10-27 (0). A person signs up in a browser (0).

### Security & auth: Soniox Speech-to-Text +19

- 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.
- Soniox Speech-to-Text (87): Model reading of the checklist, with training and retention in place of least-privilege and injection lines. "Every API key in a project has a list of permissions": real-time STT, async STT and Files with Read and Write levels, model listing, usage and temporary keys, with `permission_denied` for anything else, and temporary keys that are restricted and expire. Keys go in the WebSocket handshake rather than the URL (30). Customer audio and transcripts are never used for training, per the 1 October check (20). Audio and transcripts aren't retained by default, and async files and transcripts auto-delete after 30 days or on a delete call, per the 1 October check (15). Per-request usage logs with request IDs, duration, tokens and cost (10). SOC 2 Type 2 and ISO/IEC 27001:2022, and the Python SDK's SECURITY.md gives a disclosure route with no acknowledgement time, as soniox-tts. No security.txt (404) and no bug bounty (12). 30+20+15+10+12 = 87.

## Score by category

| Category | Weight | IBM Watson Speech to Text | Soniox Speech-to-Text | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 40 | 77 | Soniox Speech-to-Text +37 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 55 | 85 | Soniox Speech-to-Text +30 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 70 | Soniox Speech-to-Text +4 |
| Security & auth | 14% (17.5 this run) | 68 | 87 | Soniox Speech-to-Text +19 |
| 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 | 75 | Soniox Speech-to-Text +42 |
| Transparency & trust | 7% (8.8 this run) | 80 | 76 | IBM Watson Speech to Text +4 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **54.5 · C** | **68.5 · B** | |

## Facts side by side

| Fact | IBM Watson Speech to Text | Soniox Speech-to-Text |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | IBM | Soniox |
| Hosted endpoint | no (local only) | `https://api.soniox.com/v1` |
| Transports | HTTP, websocket | HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Pay per use |
| Price for speech-to-text | not published | $0.0017 per minute of audio |
| x402 | no | no |
| Licence | none | Apache-2.0 (Python SDK) |
| Tools exposed | 0 | none |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-06-29 | 2026-11-03 |
| Terms last updated | no date given | 2026-06-29 |
| Privacy policy last updated | 2026-08-25 | 2026-06-29 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | not found in the text | yes |
| Terms or service can change without notice | not found in the text | yes |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | none | 12 stars, 22k npm/wk |
| Agent reviews | none | 3.5/5 (2) |

## What the same task costs

| Task | IBM Watson Speech to Text | Soniox Speech-to-Text |
| --- | --- | --- |
| Transcribe a one-hour meeting | $0.60 to $1.20 | $0.10 to $0.12 |

## How the scores have moved

### IBM Watson Speech to Text

No score change since it was listed.

### Soniox Speech-to-Text

- +10.3 on 4 November 2026 (C to B): product, new evidence, negative event
- -0.1 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.

**Soniox Speech-to-Text.** About $0.10 an hour async and $0.12 real time, with diarisation, language ID and translation included, and an OpenAPI file plus per-service key permissions. The v6 models arrived on 3 November 2026 and v5 is removed on 15 December. No free credits for new accounts since October 2025, and a 2.x Python SDK minor removed public interfaces.

## 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

### Soniox Speech-to-Text

1. Pass `audio_url` for public files and skip the upload step. Delete uploaded files or they count against the 10 GB quota for 30 days
2. Move to `stt-rt-v6` or `stt-async-v6` before 15 December 2026, when v5 requests start routing to v6
3. Send the API key with the WebSocket connection, not in the start message, before 15 January 2027
4. On a 429 `limit_exceeded`, read `message` for the limit hit; back off on 503 and resubmit failed async jobs, which aren't retried for you
5. Split anything over 300 minutes. The cap is fixed

## Questions

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

Soniox Speech-to-Text scores 68.5 (B) on agent readiness against IBM Watson Speech to Text's 54.5 (C), and leads in 5 of 7 scored categories. IBM Watson Speech to Text leads on payments & pricing.

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

Both need an API key.

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

No hosted endpoint is listed for IBM Watson Speech to Text. Soniox Speech-to-Text has a hosted endpoint at https://api.soniox.com/v1.


## For agents

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

## Other comparisons with IBM Watson Speech to Text or Soniox Speech-to-Text

- [Amazon Transcribe vs IBM Watson Speech to Text](https://www.anchorterminal.com/compare/amazon-transcribe-vs-ibm-watson-stt.md)
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- [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)
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- [Groq Speech-to-Text vs IBM Watson Speech to Text](https://www.anchorterminal.com/compare/groq-speech-to-text-vs-ibm-watson-stt.md)
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