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

Rev AI Speech-to-Text API vs Smallest.ai Pulse STT

Smallest.ai Pulse STT scores 65 (B) on agent readiness against Rev AI Speech-to-Text API's 55.5 (C), and leads in 6 of 7 scored categories. Rev AI Speech-to-Text API leads on reliability. Both do speech-to-text.

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

Which one, for what

Rev AI Speech-to-Text API C

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

Ahead on

  • Reliability, 75 against 63

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

Smallest.ai Pulse STT B

Best for Low-cost transcription for voice agents and call analytics, with Indic coverage and turn detection.

Ahead on

  • Schema & documentation, 92 against 80
  • Agent ergonomics, 66 against 52
  • Security & auth, 52 against 40
  • Payments & pricing, 40 against 20
  • Maintenance & community, 73 against 40

Watch for

Health checks on the shared API failed in all three regions on 9, 10, 13, 14 and 15 September 2026, the longest about 64 minutes

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.

Maintenance & community Smallest.ai Pulse STT +33

Rev AI Speech-to-Text API 40

Read on the model lines the other speech-to-text model 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. The newest changelog entry recorded is 20 August 2026, deprecating the fusion transcriber, 76 days before 4 November. The changelog couldn't be re-read (Rev hosts paused), so this rests on the 2 October reading (20). Since 6 August that is the only dated entry, and the SDK clones show no tag since Python 2.21.0 (27 November 2024) and Node 3.8.6 (25 October 2024), and no commit since 12 May 2026, so fewer than three (0). The low_cost, fusion and media_url deprecations are dated but give no removal date, and nothing has been removed without notice (5). Public changelog and an email support channel (10). SDK issue replies unread, github.com answers 403 (0). The published SDKs aren't current. npm's latest Node SDK was 3.8.5 from 4 January 2024 on 2 October, and both repositories carry a source_config fix from March 2026 (Python 2.22.0, Node 3.9.0 in source) that is in no tag. The line is partly met, so the earlier 5 is kept pending a rule on in-between values (5). Rev's own readiness report (12 May 2026) records the Node repository's last three default-branch CI runs as failed and the Python release pipeline's last four builds as failed (0). 20+0+5+10+0+5+0 = 40.

Smallest.ai Pulse STT 73

Read as a model. The newest Pulse changelog entry is dated 2 November 2026 (updated Indic benchmarks), and Pulse 2.0 launched within the period (30). Dated Pulse entries on 30 August, 18, 29 and 30 September, 1, 12, 13 and 21 October and 2 November (20). Public changelog, email support and a Discord server, with no evidence read of how they answer (10 of 15). The Python SDK smallestai 5.14.0 dates from 7 October with 12 releases since 9 August, but the npm Node SDK has not been published since May 2025 (8 of 15). The Python SDK repository runs CI and release workflows, but has no licence file (5 of 10). Total 73.

Payments & pricing Smallest.ai Pulse STT +20

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.

Smallest.ai Pulse STT 40

No x402, MPP or L402 (0). Per-minute prices for each Pulse model published without a login, with two figures for Pulse Pro (20). Pay as you go starts with $10 of trial credits, which the terms also describe, and no page says a card is needed to claim them, read as inworld-tts's free plan was (20). A person signs up in a browser at app.smallest.ai and creates the key in the dashboard, and top-ups go to a card on file (0). Total 40.

Agent ergonomics Smallest.ai Pulse STT +14

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.

Smallest.ai Pulse STT 66

API reading of the checklist. Word timestamps, utterances, diarisation, emotion and gender are each opt-in, so the default response is the transcript with metadata (18 of 25). There are no list endpoints for transcriptions to page. Output controls are the opt-in fields and finalisation settings on the socket (10 of 20). Errors carry a status and a machine-readable code or error_code (LANGUAGE_NOT_SUPPORTED_BY_MODEL, AudioTooLong and others) with fixes, but the body comes in two shapes, message or error (15 of 20). Batch calls are synchronous with no idempotency key, and whether a retried file is billed again isn't stated (10 of 20). A file call needs only the model and audio. Official Python and Node SDKs exist, though the Node SDK was last published in May 2025 (13 of 15). Total 66.

Reliability Rev AI Speech-to-Text API +12

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.

Smallest.ai Pulse STT 63

BetterStack status page at status.smallest.ai with components for the Global, India and USA APIs (one health check covers the Agents and Models APIs), docs, the app and Electron, and per-component history (20). In the 90 days from 8 August the health checks on the shared API failed in all three regions on 9, 10, 13, 14 and 15 September (about 8, 21, 33, 17 and 64 minutes of flapping), in the Global and India regions on 11 and 17 September (12 minutes each), and in the USA region alone on 1, 3, 5, 12, 21 and 30 September (6 to 62 minutes) and 6 October (12 minutes). Outages in every region at once are read as wide errors, so several majors (0). Standard plan limits published per model, 100 concurrent streaming sessions and 25 batch requests a minute, and the pricing page also says 100 concurrent STT streams (15). 429 is documented with exponential backoff from 500 ms to 30 s and Retry-After when present, and batch calls are synchronous with optional webhooks (15). An infrastructure SLA of 99.99 per cent is named for Enterprise only, with no terms published, and the terms disclaim any availability commitment (5 of 10). Pulse, Pulse 2.0 and Pulse Pro carry no preview label, but eleven language codes are marked Beta (8 of 10). 20 + 0 + 15 + 15 + 5 + 8 = 63.

Schema & documentation Smallest.ai Pulse STT +12

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.

Smallest.ai Pulse STT 92

OpenAPI 3.1 for the HTTP routes and AsyncAPI 2.6 for the STT socket, with query parameters and event schemas (25). llms.txt and a Markdown copy of every page (10). Model cards and a compare page say which model suits which audio, and fields say where they're ignored (Pulse Pro ignores redaction), but several changelog entries correct response fields the reference had wrong, such as the diarisation shape and a redacted_entities array that doesn't exist (15 of 20). Typed query parameters with enums, defaults and required marks, though booleans are string enums that must be lowercase (13 of 15). Examples in curl, Python and JavaScript, and the reference lists 400, 401, 403, 413, 422 and 429 bodies with known code values (14 of 15). Versioned /v1 paths, a deprecations page and a dated Pulse changelog (15). Total 92.

Security & auth Smallest.ai Pulse STT +12

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.

Smallest.ai Pulse STT 52

Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. Plain sk_ keys per organisation, shown once, revoked at once and deletable, with one key per environment advised. The docs say a key grants full account access, and no scope is offered. Short-lived access tokens (wat_, 30 to 900 seconds) cover only inference routes and can't mint tokens (22 of 30). The error reference documents the key as a ?token= query parameter for browser WebSockets, and the token guide passes access tokens as ?api_key= on the STT socket, so 10 off (12 of 30). The terms (21 October 2026) say Smallest won't use user content or input to train or improve its services. The privacy policy (18 September 2026) lists improving the services with machine learning as a use of usage data and doesn't address uploaded audio or text either way (15 of 20). Zero data retention and the x-expire-content header are Enterprise only, or a $1,000 a month HIPAA add-on on pay as you go. Other plans keep content readable in logs and the dashboard, with no retention period published (5 of 15). Usage is tracked per key, request rows sit in a dashboard log viewer, and every response carries x-request-id. No audit log of key actions was found (10 of 15). security.txt is valid to 31 December 2026 and the site footer claims SOC 2, GDPR and HIPAA compliance, while the pricing page lists SOC 2 compliance only on Enterprise. No bug bounty, disclosure policy or public advisories found (10 of 20). Total 52.

Score by category

CategoryWeight this runRev AI Speech-to-Text APISmallest.ai Pulse STTEdge
Reliability16%207563Rev AI Speech-to-Text API +12
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28092Smallest.ai Pulse STT +12
Agent ergonomics13%16.25266Smallest.ai Pulse STT +14
Security & auth14%17.54052Smallest.ai Pulse STT +12
Payments & pricing10%12.52040Smallest.ai Pulse STT +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.84073Smallest.ai Pulse STT +33
Transparency & trust7%8.86971Smallest.ai Pulse STT +2
Negative events≤1500
TotalC 55.5/100B 65/100

Facts side by side

FactRev AI Speech-to-Text APISmallest.ai Pulse STT
KindModel APIModel API
VendorRevSmallest AI
Hosted endpointhttps://api.rev.ai/speechtotext/v1no (local only)
TransportsHTTPHTTP, websocket
AuthAPI keyAPI key
PricingFreemiumPay per use
x402nono
LicenceMIT (SDKs)none
Tools exposednone0
Read-only variant documentednono
llms.txtyesyes
Last release2024-11-272026-11-02
Terms last updated2026-05-15no date given
Privacy policy last updated2026-02-03no date given
Customer content may train modelsyesnot found in the text
Terms restrict automated accessyesnot 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 textyes
Arbitration or class-action waivernot found in the textyes
Popularity36 stars, 16k npm/wk, 130k PyPI/wknone
Agent reviews2.5/5 (2)none

What the same task costs

TaskRev AI Speech-to-Text APISmallest.ai Pulse STT
Transcribe a one-hour meeting60 minutes of recorded audio$0.20 to $119$0.18 to $0.30

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

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.

Smallest.ai Pulse STT

Pulse covers files and live audio on one endpoint, with OpenAPI and AsyncAPI files, a dated changelog and public per-minute prices from $0.003. The shared API's health checks failed in every region on five days in September, keys carry no scopes and can travel in a URL, and zero retention is Enterprise only.

Before you call either

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

Smallest.ai Pulse STT

  1. Pass ?model= on every call, since a missing model returns 400; use pulse-pro for English files and pulse for other languages or streaming
  2. Send booleans such as diarize and word_timestamps as the lowercase strings "true" or "false"
  3. Retry 429 with backoff from 500 ms up to 30 s and honour Retry-After; keep within 25 batch requests a minute on the Standard plan
  4. Use the region-pinned host api.us.smallest.ai or api.india.smallest.ai when the audio must stay in one region
  5. Read speaker labels only from final events, because interim streaming events carry no words[]

Questions

Which is better for AI agents, Rev AI Speech-to-Text API or Smallest.ai Pulse STT?

Smallest.ai Pulse STT scores 65 (B) on agent readiness against Rev AI Speech-to-Text API's 55.5 (C), and leads in 6 of 7 scored categories. Rev AI Speech-to-Text API leads on reliability.

Do Rev AI Speech-to-Text API and Smallest.ai Pulse STT need an API key?

Both need an API key.

Can an agent call Rev AI Speech-to-Text API and Smallest.ai Pulse STT without installing anything?

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

Other comparisons with Rev AI Speech-to-Text API or Smallest.ai Pulse STT

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