Head to head · Speech-to-text · October 2026 research run

Google Cloud Speech-to-Text vs Inworld STT

Google Cloud Speech-to-Text scores 66.6 (B) on agent readiness against Inworld STT's 54.7 (C), and leads in 5 of 7 scored categories. Inworld STT leads on payments & pricing and maintenance & community. Both do speech-to-text.

Best speech-to-text APIs for AI agents · All 320 stt comparisons

Which one, for what

Google Cloud Speech-to-Text B

Best for Google Cloud teams with audio already in Cloud Storage who want no training and no retention by default.

Ahead on

  • Reliability, 75 against 60
  • Schema & documentation, 80 against 54
  • Agent ergonomics, 70 against 56
  • Security & auth, 85 against 63
  • Transparency & trust, 87 against 60

Also in its favour

  • A hosted endpoint, with nothing to install

Watch for

No release note since 2025-11-13

Inworld STT C

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

Ahead on

  • Payments & pricing, 40 against 20
  • Maintenance & community, 41 against 25

Also in its favour

  • Free to start without a card

Watch for

No OpenAPI or other machine-readable contract

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Transparency & trust Google Cloud Speech-to-Text +27

Google Cloud Speech-to-Text 87

Closed service under the Google Cloud terms (15). The data logging page, the terms and the privacy notice agree that audio isn't used for training without opt-in, and a data processing addendum and sub-processor list exist (25). Google Cloud's terms carry a notice period before a GA capability is discontinued, but we found no dated Speech-to-Text deprecation notices (15). us and eu multi-region endpoints and a public sub-processor list (20).

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.

Schema & documentation Google Cloud Speech-to-Text +26

Google Cloud Speech-to-Text 80

The API surface is public as protocol buffers and a discovery document, a machine-readable contract (25). No llms.txt found (0). Method descriptions state purpose, and the model pages say which model suits which audio, but not when to avoid sync or streaming (15). Typed proto messages with enums and required fields, no free-form blobs (15). Errors follow Google's standard status codes, with samples in the docs but little per-method error detail (10). Versioned v1 and v2 with release notes (15). The V2 discovery document read on 1 November is revision 20261001, with 26 methods and 69 schemas.

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.

Security & auth Google Cloud Speech-to-Text +22

Google Cloud Speech-to-Text 85

Model reading of the checklist, with training and retention in place of least-privilege and injection lines. OAuth 2.0 with service accounts and IAM roles, scoped per project, no API key in the documented V2 flow. The token can also travel in the URL. Google's OAuth guide accepts it as an access_token query parameter, the V2 discovery document (revision 20261001) lists access_token, oauth_token and key as query parameters, and on 1 November speech.googleapis.com/v2/projects/example-project/locations/global/recognizers answered 401 "missing required authentication credential" with no token and 401 "invalid authentication credentials" with a made-up ?access_token=, so the token is read from the query string. That takes the 10-point deduction, as every Google API listing does in this run (Gmail, Sheets, Drive and Calendar on 17 October, Ads, Model Armor, Secret Manager and Document AI on 1 November) (20). Audio isn't used for training unless the project opts in to data logging (20). Streaming and sync audio is processed in memory and not stored, and batch results are kept for a short window (15). Cloud Audit Logs cover Google Cloud APIs, though we didn't confirm which Speech methods they record (10). Valid security.txt, Google's vulnerability reward programme, SOC 2 and ISO 27001, and public Cloud security bulletins (20). 20 + 20 + 15 + 10 + 20 = 85.

Inworld STT 63

Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. Workspace API keys sent as Basic credentials, deleted to revoke, with separate keys per environment advised. The CLI mints read-only keys unless --write is given, but write toggles cover only the Voice and Router APIs, so no key is limited to one product. Browsers use short-lived tokens minted server side, via the bearer_ WebSocket subprotocol, not the URL (25 of 30). The Terms (11 June 2025) say Inworld won't train generally available models on customers' non-public Materials, except feedback and flagged content, while the Privacy Notice (18 January 2026) lists training AI models among its uses, per the inworld-tts check of 4 November (12 of 20). Zero data retention keeps STT audio and transcripts in memory and out of logs, included on Developer ($300 a month) and above per the docs, while the STT page says Enterprise or a Growth add-on. Async results and audio go after 7 days, and no default period is given for logs (8 of 15). Usage is attributed per key and a Performance page shows errors and throttling (8 of 15). SOC 2 Type II and HIPAA claimed and a vulnerability report form, with no security.txt or bug bounty, per the 4 November reading (10 of 20). Total 63.

Payments & pricing Inworld STT +20

Google Cloud Speech-to-Text 20

No x402, MPP or L402 (0). Per-minute prices with volume tiers published without a login (20). The 60 free V1 minutes and the $300 new-account credit both need a billing account with a card (0). A person signs up in a browser (0).

Inworld STT 40

No x402, MPP or L402 (0). Per-hour prices for every plan published without a login (20). On-Demand includes up to 400 minutes of STT and lists no payment method, while async jobs need one (20). A person signs up in the Portal or through inworld login in a browser before a key exists (0). Total 40.

Maintenance & community Inworld STT +16

Google Cloud Speech-to-Text 25

The newest release note is still 2025-11-13, Chirp 3 preview in four more regions (page last updated 26 October 2026), 353 days ago (0). In the 90 days from 3 August we counted no release note and one Python client release, google-cloud-speech 2.41.0 on 1 October, whose only change is declaring Python 3.15 support. A release that doesn't change the service counts half on the 90-day line and can't set the recency line, so neither line moves (0). The last client release that touched the API was 2.37.0 on 26 February 2026 (endpointing sensitivity for streaming). Release notes, a public issue tracker and paid support (10). Official client libraries in seven or more languages (10). Package CI not checked (5). 0 + 0 + 10 + 10 + 5 = 25.

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.

Reliability Google Cloud Speech-to-Text +15

Google Cloud Speech-to-Text 75

Google Cloud status page with a per-product history (20). One incident lists Speech-to-Text in the 90 days from 3 August, the europe-west2 incident of 20 October, 06:00 to 12:08 UTC, which named 38 products in that one region. A single-region incident is partial and read as minor, as this run reads partial incidents. The other three Google Cloud incidents since 3 August (20 August, 1 September, 8 and 9 October) don't list Speech-to-Text. The public page only shows broad incidents. Minor only (20). Quotas published with numbers, 300 concurrent streams, 300 sync and 150 batch requests a minute per region, streams up to 5 minutes and sync up to 1 minute (15). The Speech quotas page (last updated 26 October 2026) still says nothing about the error a quota breach returns or how to back off, and we don't count Google's general API design guide for this API (0). Speech-to-Text SLA of 99.9 per cent monthly uptime with credits of 10 to 50 per cent, per the 1 October check, not re-read on 1 November (10). Chirp 3 GA since 2025-10-13 in us and eu, though 82 of its 111 locales were preview on 1 October (10). 20 + 20 + 15 + 0 + 10 + 10 = 75.

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.

Score by category

CategoryWeight this runGoogle Cloud Speech-to-TextInworld STTEdge
Reliability16%207560Google Cloud Speech-to-Text +15
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28054Google Cloud Speech-to-Text +26
Agent ergonomics13%16.27056Google Cloud Speech-to-Text +14
Security & auth14%17.58563Google Cloud Speech-to-Text +22
Payments & pricing10%12.52040Inworld STT +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.82541Inworld STT +16
Transparency & trust7%8.88760Google Cloud Speech-to-Text +27
Negative events≤1500
TotalB 66.6/100C 54.7/100

Facts side by side

FactGoogle Cloud Speech-to-TextInworld STT
KindModel APIModel API
VendorGoogle CloudInworld AI
Hosted endpointhttps://speech.googleapis.com/v2no (local only)
TransportsHTTPHTTP, websocket
AuthOAuthAPI key
PricingFreemiumPay per use
Price for speech-to-textnot published$0.0017 per minute of audio
x402nono
LicenceApache-2.0 (SDKs)none
Tools exposednone0
Read-only variant documentednono
llms.txtnoyes
Last release2026-10-012026-10-29
Terms last updated2026-09-022025-06-11
Privacy policy last updated2026-10-012026-01-18
Customer content may train modelsyesnot found in the text
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingnot found in the textnot found in the text
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waivernot found in the textnot found in the text
Popularity713k npm/wk, 3.7M PyPI/wknone
Agent reviews3/5 (2)none

What the same task costs

TaskGoogle Cloud Speech-to-TextInworld STT
Transcribe a one-hour meeting60 minutes of recorded audio$0.18 to $4.68$0.10 to $0.15

Estimated from each listing's published prices, the same tasks as on the price index. Plans, minimums and free allowances aren't counted.

How the scores have moved

Verdicts

Google Cloud Speech-to-Text

Audio isn't stored or used for training unless the project opts in to data logging. No release note since 2025-11-13.

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

Google Cloud Speech-to-Text

  1. Call Chirp 3 on the us or eu endpoint. It isn't listed for the global location
  2. Reopen streams before the 5-minute limit, or use BatchRecognize for recordings
  3. Downmix stereo unless you need channel labels, since each channel is billed
  4. Set dynamic batch on offline jobs to cut the price from $0.016 to $0.003 a minute
  5. Send the OAuth token in the Authorization: Bearer header, never as ?access_token=, and back off on RESOURCE_EXHAUSTED

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, Google Cloud Speech-to-Text or Inworld STT?

Google Cloud Speech-to-Text scores 66.6 (B) on agent readiness against Inworld STT's 54.7 (C), and leads in 5 of 7 scored categories. Inworld STT leads on payments & pricing and maintenance & community.

Do Google Cloud Speech-to-Text and Inworld STT need an API key?

Google Cloud Speech-to-Text uses an OAuth sign-in. Inworld STT needs an API key.

Can an agent call Google Cloud Speech-to-Text and Inworld STT without installing anything?

Google Cloud Speech-to-Text has a hosted endpoint at https://speech.googleapis.com/v2. No hosted endpoint is listed for Inworld STT.

Other comparisons with Google Cloud Speech-to-Text or Inworld STT

Machine-readable

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