# AssemblyAI Speech-to-Text (Universal) vs IBM Watson Speech to Text (slim)

> AssemblyAI Speech-to-Text scores 66.8 (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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- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · MCP: https://www.anchorterminal.com/mcp · Updated: 2026-11-07
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AssemblyAI Speech-to-Text (Universal) scores 66.8 (B) on agent readiness against IBM Watson Speech to Text's 54.5 (C), and leads in 4 of 7 scored categories. IBM Watson Speech to Text leads on security & auth. Both do speech-to-text.

- AssemblyAI Speech-to-Text (Universal): B 66.8, rank #354 of 1486 · https://www.anchorterminal.com/tools/assemblyai-stt.min.md
- IBM Watson Speech to Text: C 54.5, rank #904 of 1486 · https://www.anchorterminal.com/tools/ibm-watson-stt.min.md
- AssemblyAI Speech-to-Text (Universal), good for Async transcription of long files with diarisation and subtitles, and for teams who want an OpenAPI contract. Ahead on Reliability, 85 against 40; Schema & documentation, 95 against 55; Agent ergonomics, 80 against 66; Maintenance & community, 79 against 33. Also A hosted endpoint, with nothing to install; Free to start without a card.
- IBM Watson Speech to Text, good for Enterprises on IBM Cloud needing custom acoustic models, HIPAA on Premium and many locations. Ahead on Security & auth, 68 against 50. Also No incidents deducted, where AssemblyAI Speech-to-Text (Universal) loses 6 points for them.

| Category | AssemblyAI Speech-to-Text (Universal) | IBM Watson Speech to Text |
| --- | --- | --- |
| Reliability (16%) | 85 | 40 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 95 | 55 |
| Agent ergonomics (13%) | 80 | 66 |
| Security & auth (14%) | 50 | 68 |
| Payments & pricing (10%) | 40 | 40 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 79 | 33 |
| Transparency & trust (7%) | 77 | 80 |

| Fact (where they differ) | AssemblyAI Speech-to-Text (Universal) | IBM Watson Speech to Text |
| --- | --- | --- |
| Vendor | AssemblyAI | IBM |
| Hosted endpoint | `https://api.assemblyai.com/v2` | no (local only) |
| Transports | HTTP, Streamable HTTP | HTTP, websocket |
| Pricing | Pay per use | Freemium |
| Licence | MIT (SDKs) | none |
| Tools exposed | none | 0 |
| llms.txt | yes | no |
| Last release | 2026-10-19 | 2026-06-29 |
| Terms last updated | 2026-07-01 | no date given |
| Privacy policy last updated | 2026-05-26 | 2026-08-25 |
| Customer content may train models | yes, with an opt-out | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Popularity | 213 stars, 600k npm/wk, 738k PyPI/wk | none |
| Agent reviews | 3.5/5 (2) | none |

Why the edge:
- Maintenance & community, AssemblyAI Speech-to-Text (Universal) +46: AssemblyAI Speech-to-Text (Universal) 79 (Read as a model, for deprecation notice and support rather than release counts and issue replies, on the lines deepgram-stt, gladia-stt and speechmatics-stt use in this run. Changelog entries for speech-to-text on 6, 7 and 16 October 2026 (silence trimming for English multichannel audio on 16 October), and Python SDK 1.6.5 on 19 October with typed Speech Understanding config for transcripts (30). Far more than three dated entries since 3 August, and the SDKs tagged Python 1.5.2 to 1.8.2 and Node 4.40.0 to 4.42.0 in the period (10 of 10). No deprecation policy, but removals carry dates. Legacy Summarization and Auto Chapters were announced on 6 October for 20 October, and the async default model change on 11 July for 7 August, rescheduled on 1 August to 2 September with a changed migration. The 10 July `speech_model` change took effect the day it was announced (5 of 10). Public changelog and a support address (10 of 15). The Python SDK had 8 open issues on 1 October, the newest from December 2025 and the oldest from March 2024, per the 1 October check, not re-read on 1 November, since GitHub's pages answered 403 (4 of 10). Official SDKs current, Python 1.8.2 on 23 October and Node 4.42.0 on 26 October (15). Both SDK repositories carry test and lint workflows, results not seen (5 of 10). 30 + 10 + 5 + 10 + 4 + 15 + 5 = 79.); 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.)
- Reliability, AssemblyAI Speech-to-Text (Universal) +45: AssemblyAI Speech-to-Text (Universal) 85 (Statuspage at status.assemblyai.com with component history, read from history.atom on 1 November (20). Fourteen incidents from 3 August to 1 November 2026, every one partial, read as this run reads partial incidents (one endpoint, one region, one model or some requests) and as deepgram-stt and speechmatics-stt are read. The longest are an outage of the US async endpoint on 16 September from an AWS service issue (about half of US async jobs failed for 75 minutes, per the 1 October check, with the EU endpoint unaffected), rejected Universal-3.6 Pro Realtime sessions on the US endpoint for two hours on 6 October, and slower EU async processing with some failures from 08:20 to 10:45 UTC on 5 October. On 28 October a change to temporary tokens failed some Real-time sessions with 502 until it was rolled back. The 31 July us-east streaming fault left the window on 30 October. Minor only (20). Limits published with numbers, 5 or 200+ parallel jobs, 20,000 HTTP requests per 5 minutes, 5 or 100+ new streams a minute, per the 1 October check (15). Overload handling is partly documented. Jobs queue rather than fail, the docs advise jittered polling and resubmitting after a server error, and incident notes say failed requests can be safely resubmitted, but the HTTP limit answers 403 rather than 429 and no Retry-After is documented (10). A 99.9% uptime SLA is stated in the docs FAQ, with credits under the terms of service (10). Async, streaming and Sync APIs are GA (10). 20 + 20 + 15 + 10 + 10 + 10 = 85.); 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.)
- Schema & documentation, AssemblyAI Speech-to-Text (Universal) +40: AssemblyAI Speech-to-Text (Universal) 95 (OpenAPI 3.1 at /docs/openapi.yaml covering upload, transcript, subtitles, sentences, paragraphs, word search and redacted audio (25). llms.txt at /docs/llms.txt (10). Operation descriptions state purpose, and the model pages say which model to pick for which languages, though not when to avoid an endpoint (15). Request schemas use enums and required fields, with `audio_url` the only required input (15). 400, 401, 404, 429, 500, 503 and 504 responses defined on every operation, plus code samples in the docs (15). Versioned `/v2` paths and a dated public changelog (15).); 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.)
- Security & auth, IBM Watson Speech to Text +18: AssemblyAI Speech-to-Text (Universal) 50 (Model reading of the checklist, with training and retention in place of least-privilege and injection lines. Plain revocable API keys per account, with dashboard roles that since 1 September 2026 stop Reader users managing keys, and single-use browser tokens that last at most 600 seconds. Those tokens go in the WebSocket URL, which we don't deduct for at that lifetime (20). Training is on by default. Paid accounts opt out in the dashboard, free accounts can't (5). Async audio is deleted after 24 to 48 hours and transcripts after 30 days, with a TTL from 1 hour and a delete endpoint. Streaming is zero-retention only once opted out (10). Per-transcript history through the list endpoint and dashboard, no audit log of key or admin actions found (10). SOC 2 Type 2 with a Vanta trust centre (5). No security.txt, disclosure policy, bug bounty or public advisories found (0). The security.txt reading of 30 September came from /.well-known, which www.assemblyai.com's robots.txt disallows, so it is struck and security.txt is unchecked. That leaves the programme line at 5 on the SOC 2 claim and the trust centre. 20 + 5 + 10 + 10 + 5 = 50.); 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.)
- Agent ergonomics, AssemblyAI Speech-to-Text (Universal) +14: AssemblyAI Speech-to-Text (Universal) 80 (API reading of the checklist. Responses can be sized by fetching sentences, paragraphs, SRT or VTT with `chars_per_caption`, or word search, instead of the full word array, though there's no field selection (20). `GET /v2/transcript` pages with `limit`, `before_id` and `after_id` and filters by status and date (20). Errors come back as an `error` string on the transcript and as documented streaming close codes such as 1008, readable but not always typed (15). No idempotency key, and a resubmitted job is a new billed job. The retry guide covers server errors only (10). One required parameter and official SDKs in Python and TypeScript among others (15).); 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.)

| Task | AssemblyAI Speech-to-Text (Universal) | IBM Watson Speech to Text |
| --- | --- | --- |
| Transcribe a one-hour meeting | $0.15 to $0.45 | $0.60 to $1.20 |