# Gladia Speech-to-Text API + MCP vs Inworld STT

> Gladia Speech-to-Text scores 69.8 (B) to Inworld STT's 54.7 (C) for speech-to-text. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/gladia-stt-vs-inworld-stt
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- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
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- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
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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

Gladia Speech-to-Text API + MCP scores 69.8 (B) on agent readiness against Inworld STT's 54.7 (C), and leads in 6 of 7 scored categories. Both do speech-to-text.

- Gladia Speech-to-Text API + MCP: grade B, 69.8/100, rank #226 of 1510. Markdown https://www.anchorterminal.com/tools/gladia-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/gladia-stt.json
- Inworld STT: grade C, 54.7/100, rank #900 of 1510. Markdown https://www.anchorterminal.com/tools/inworld-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/inworld-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

### Gladia Speech-to-Text API + MCP (B)

Good for: Multilingual meetings and calls where live and async transcription in 100+ languages is needed, and for teams who want an MCP server.

Ahead on:
- Reliability, 70 against 60
- Schema & documentation, 95 against 54
- Agent ergonomics, 75 against 56
- Maintenance & community, 70 against 41
- Transparency & trust, 65 against 60

Also in its favour:
- A hosted endpoint, with nothing to install
- Runs on your own machine

Watch for: Self-serve audio is used for model training by default unless the account opts out

### Inworld STT (C)

Good for: Low-cost live transcription for voice agents, with speaker traits.

Watch for: No OpenAPI or other machine-readable contract


## Why the edge

### Schema & documentation: Gladia Speech-to-Text API + MCP +41

- Gladia Speech-to-Text API + MCP (95): OpenAPI file at api.gladia.io/openapi.json (25). llms.txt (10). Reference pages state purpose per endpoint and the model page says to use `solaria-3` only for async English, French, German, Spanish or Italian (15). Typed bodies with enums and required fields, `audio_url` the only required input for pre-recorded (15). Examples per endpoint and documented error codes (15). Versioned `/v2` paths and a dated changelog (15).
- Inworld STT (54): No OpenAPI or other machine-readable file. The usual spec paths redirect, and the reference pages are Markdown (0). llms.txt, Markdown twins and a docs MCP server (10). Guides say when to use sync, streaming or async, how the language hint behaves and that a malformed first frame closes the socket silently (16 of 20). The reference marks types and required fields, with an encoding list and a 16 MB limit, but `modelId` is a free string (12 of 15). Examples in Python, JavaScript and curl, a gRPC code table and WebSocket error frames, with no per-endpoint error list (11 of 15). Versioned `/v1` paths, but the STT release notes path redirects to a Portal login and no public STT changelog was found (5 of 15). Total 54.

### Maintenance & community: Gladia Speech-to-Text API + MCP +29

- Gladia Speech-to-Text API + MCP (70): Read as a model, for deprecation notice and model churn rather than release counts, on the lines deepgram-stt was settled on in this run. SDK 2.2.0 on 13 October 2026, three fixes among them limiting list pagination to the configured API, 19 days before 1 November (30). 2.2.1 on 23 October only raises the Python `certifi` floor to distrust a compromised certificate authority and is a version bump with no code changes for JavaScript, so as a dependency-only release it counts half and doesn't set this line, as azure-translator's was read. In the 90 days from 3 August, changelog entries on 8, 9 and 14 September, SDK 2.1.0 (18 and 21 September), 2.2.0 and 2.2.1 (at half), and the MCP server 0.1.0 and 0.1.1 on 24 September (10). The `/v2/transcription` endpoints are marked deprecated in favour of `/v2/pre-recorded` with no removal date, structured data extraction has gone from the OpenAPI file without a changelog entry, and no deprecation policy was found (0 of 10). Public changelog, help centre and Discord (10 of 15). SDK and MCP repository issues couldn't be read, since github.com refuses our reader, so absent (0 of 10). Official JavaScript and Python SDKs current at 2.2.1 (15). The SDK repository has CI, release and OpenAPI type-update workflows, results not seen (5 of 10). 30 + 10 + 0 + 10 + 0 + 15 + 5 = 70.
- Inworld STT (41): Read as a model. No public STT changelog. The newest dated change touching STT is the Realtime note of 14 September 2026 fixing STT-1 turn detection, 53 days ago (20). The CLI, which carries the STT command and MCP tool, shipped 1.4.0 to 1.5.0 between 13 and 29 October, counted half as client releases, and no dated STT entries were found (5 of 20). Discord and support@inworld.ai, with no evidence of answers read (6 of 15). No official STT SDK; the CLI is current (5 of 15). CLI on npm under MIT, current, CI not read (5 of 10). Total 41.

### Agent ergonomics: Gladia Speech-to-Text API + MCP +19

- Gladia Speech-to-Text API + MCP (75): API reading of the checklist. Add-ons such as summaries, NER and translation are opt-in, so a plain request stays small, but there's no field selection (15). Pre-recorded jobs list with offset, limit and filters (20). Documented error codes, with a 429 for concurrency (15). No idempotency key. The docs warn that a job is already queued once the 200 or `transcription.created` webhook arrives, which is safe-retry guidance of a sort (10). One required parameter and official SDKs in JavaScript and Python (15). The official MCP server adds 8 tools for async jobs, which this API reading doesn't score.
- Inworld STT (56): API reading of the checklist. Voice Profile, word timestamps and diarisation are opt-in, and responses carry a `usage` block (18 of 25). No lists to page. Async jobs return an operation to poll (8 of 20). Errors carry a numeric gRPC code and message on both endpoints, but a malformed first message closes the socket with 1005 and no frame (12 of 20). Sync calls are stateless and async calls return an operation, with no idempotency key, and empty transcripts and add-ons are billed (10 of 20). A call needs a model, an encoding and the audio. No STT SDK was found, only the CLI and its MCP server and REST examples (8 of 15). Total 56.

### Reliability: Gladia Speech-to-Text API + MCP +10

- Gladia Speech-to-Text API + MCP (70): incident.io status page with per-component uptime bars and incident pages, and an RSS feed read on 1 November (20). One major incident in the 90 days from 3 August, a global Pre-Recorded and Real-Time incident on 23 September 2026 from 07:05 to 08:10 caused by a provider network fault, as read on 1 October. The rest are partial and read as minor, a 20-minute full outage and a timeouts incident on 22 September, slower processing on the afternoon of 23 September, and Europe-only degradations on 2, 10, 14 to 15 (elevated errors and timeouts in Europe from 09:07 on 14 September to 13:58 on 15 September), 21, 22 and 28 September and on 3, 4 and 7 October (Pre-Recorded v2 in Europe) (10). Concurrency limits published with numbers, 25 parallel async jobs plus 300 queued and 30 live sessions on paid plans, 3 and 1 on free (15). The docs say a 429 means the concurrency limit, but we found no backoff guidance or Retry-After (5). The pricing page's plan comparison, read on 1 November, lists a 99.9% uptime SLA for Enterprise (10). `solaria-1` and `solaria-3` are GA (10). 20 + 10 + 15 + 5 + 10 + 10 = 70.
- Inworld STT (60): Hosted reading of the checklist. status.inworld.ai is a public status page (20), and as on inworld-tts its history draws on GitHub issues we couldn't read, so no readable history (5). Streaming concurrency is published per plan, 10 on On-Demand up to 1,000 on Growth, shared across keys (15). 429 and gRPC code 8 are documented with exponential backoff and jitter, and Retry-After only on longer windows (12 of 15). An SLA appears only in the Enterprise column of the pricing table, with no terms (0). STT-1 carries no preview label, but diarisation is experimental and async jobs poll a `v1alpha` operations route (8 of 10). 20 + 5 + 15 + 12 + 0 + 8 = 60.

### Transparency & trust: Gladia Speech-to-Text API + MCP +5

- Gladia Speech-to-Text API + MCP (65): Closed service with an MIT SDK and MCP server and separate terms for Gladia SAS and Gladia Inc. (15). The statements disagree. The security page gives a 12-month default retention with custom policies for customers and says only Free plan data trains models, while the retention page gives 1 year on free, 3 weeks on paid and zero retention only on Enterprise, and the pricing page says Self-serve is opted in to training by default. ISO 27001 is described as in progress (15). Breaking changes are flagged with dates in the changelog, such as SDK 2.0.0 and the move to credit billing on 3 July 2026 with a 6 to 20 July rollout, but no deprecation policy was found (10). Hosting with a French provider is stated, and no sub-processor list was found (10).
- Inworld STT (60): Closed service with clear terms naming Theai, Inc. dba Inworld AI (15). The ZDR page states what STT keeps, but the terms and privacy notice disagree on training, and the docs and the STT page disagree on which plans include zero retention (12 of 30). No dated STT deprecation or change notices are public (8 of 20). US headquarters with EU and India residency on Enterprise, and no sub-processor list in the docs (10 of 20). Total 45.

## Score by category

| Category | Weight | Gladia Speech-to-Text API + MCP | Inworld STT | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 70 | 60 | Gladia Speech-to-Text API + MCP +10 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 95 | 54 | Gladia Speech-to-Text API + MCP +41 |
| Agent ergonomics | 13% (16.2 this run) | 75 | 56 | Gladia Speech-to-Text API + MCP +19 |
| Security & auth | 14% (17.5 this run) | 65 | 63 | Gladia Speech-to-Text API + MCP +2 |
| 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) | 70 | 41 | Gladia Speech-to-Text API + MCP +29 |
| Transparency & trust | 7% (8.8 this run) | 65 | 60 | Gladia Speech-to-Text API + MCP +5 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **69.8 · B** | **54.7 · C** | |

## Facts side by side

| Fact | Gladia Speech-to-Text API + MCP | Inworld STT |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Gladia | Inworld AI |
| Hosted endpoint | `https://api.gladia.io/v2` | no (local only) |
| Transports | HTTP, stdio | HTTP, websocket |
| 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 | MIT (SDKs and MCP server) | none |
| Tools exposed | 8 | 0 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-23 | 2026-10-29 |
| Terms last updated | no date given | 2025-06-11 |
| Privacy policy last updated | no date given | 2026-01-18 |
| 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 | 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 | 4 stars, 4.8k npm/wk, 126k PyPI/wk | none |
| Agent reviews | 3/5 (2) | none |

## How the scores have moved

### Gladia Speech-to-Text API + MCP

- +0.2 on 1 November 2026: terms, correction
- +0.1 on 27 October 2026: checklist
- -0.2 on 8 October 2026: checklist

### Inworld STT

No score change since it was listed.

## Verdicts

**Gladia Speech-to-Text API + MCP.** The `solaria-1` model transcribes live and recorded audio in over 100 languages with code switching, behind an OpenAPI file and SDKs in two languages. Self-serve audio is used for model training unless the account opts out, and Gladia's pages disagree on retention and training defaults.

**Inworld STT.** Inworld STT costs $0.10 to $0.15 an hour with 400 free minutes, and covers files, live streams and async jobs in 30 languages with Voice Profile signals. There is no machine-readable spec, no public STT changelog and no readable status history, and diarisation is still experimental.

## Before you call either

### Gladia Speech-to-Text API + MCP

1. Don't resubmit a pre-recorded job after a 200 or a `transcription.created` webhook. It's already queued
2. Pick `solaria-3` only for async EN, FR, DE, ES or IT audio. Anything live or multilingual needs `solaria-1`
3. A 429 means the concurrency limit, 3 async and 1 live on the free plan. Wait for a running job to finish
4. Opt the account out of model training in its profile before sending sensitive audio on Self-serve
5. Split files over 135 minutes or 1,000 MB

### Inworld STT

1. Send the Base64 credential as-is in `Authorization: Basic`; don't encode it again
2. Wrap the first WebSocket message in `transcribeConfig`, because a malformed first frame closes the socket with 1005 and no error
3. Use `POST /stt/v1/transcribe:async` for files over about 16 MB and collect the transcript within 7 days
4. Retry 429 or gRPC code 8 with exponential backoff and jitter, and stay within the plan's streaming concurrency
5. Stop sending audio when nobody speaks, since streams are billed for every second sent

## Questions

### Which is better for AI agents, Gladia Speech-to-Text API + MCP or Inworld STT?

Gladia Speech-to-Text API + MCP scores 69.8 (B) on agent readiness against Inworld STT's 54.7 (C), and leads in 6 of 7 scored categories.

### Do Gladia Speech-to-Text API + MCP and Inworld STT need an API key?

Both need an API key.

### Can an agent call Gladia Speech-to-Text API + MCP and Inworld STT without installing anything?

Gladia Speech-to-Text API + MCP has a hosted endpoint at https://api.gladia.io/v2. No hosted endpoint is listed for Inworld STT.


## For agents

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

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- [Inworld STT vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/inworld-stt-vs-soniox-stt.md)
- [Inworld STT vs Speechmatics Speech-to-Text](https://www.anchorterminal.com/compare/inworld-stt-vs-speechmatics-stt.md)

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