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

Deepgram Speech-to-Text (Nova-3, Flux) vs Smallest.ai Pulse STT

Deepgram Speech-to-Text (Nova-3, Flux) scores 74.4 (BB) on agent readiness against Smallest.ai Pulse STT's 65 (B), and leads in 5 of 7 scored categories. Both do speech-to-text.

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

Which one, for what

Deepgram Speech-to-Text (Nova-3, Flux) BB

Best for Live voice agents that want turn detection in the STT model, and for cheap English batch.

Ahead on

  • Reliability, 80 against 63
  • Agent ergonomics, 75 against 66
  • Security & auth, 72 against 52
  • Transparency & trust, 78 against 71

Also in its favour

  • Agent-ready, a grade of BB or better
  • A hosted endpoint, with nothing to install
  • Runs on your own machine
  • Free to start without a card

Watch for

Training on audio is the default and the opt-out is a per-request flag

Smallest.ai Pulse STT B

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

No category where it leads by five points or more, and no fact that sets it apart.

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.

Security & auth Deepgram Speech-to-Text (Nova-3, Flux) +20

Deepgram Speech-to-Text (Nova-3, Flux) 72

Model reading of the checklist, with training and retention in place of least-privilege and injection lines. Keys belong to a project, carry a role and can expire on a date or after a set duration. Browser JWTs live 30 seconds and travel in a header (30). Requests may be kept for model training under the Model Improvement Program unless each request sets mip_opt_out=true, which any account can do (10). Opted-out requests are kept only for processing, so zero retention is self-serve but not the default (10). Per-request logs and usage data in the console and API, no audit log of key actions found (10). SOC 2 Type 1 and Type 2 (certificates on request) and HIPAA with a BAA on the compliance page. deepgram.com now serves a valid security.txt (Contact security@deepgram.com, Expires 30 September 2027), not found on 30 September. No disclosure policy, bug bounty or public advisories found. The 1 October check gave this line 5 where deepgram-tts and deepgram-voice-agent gave 10 and 12 on the same compliance page, so it's read as deepgram-tts was on 1 November (12 of 20). 30 + 10 + 10 + 10 + 12 = 72.

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.

Reliability Deepgram Speech-to-Text (Nova-3, Flux) +17

Deepgram Speech-to-Text (Nova-3, Flux) 80

Statuspage at status.deepgram.com with component history and an RSS feed (20). Nine incidents in the 90 days from 3 August touch speech-to-text, every one partial, read as this run reads partial incidents (one model, one region, one datacenter or some requests) and as deepgram-tts is read. Degraded batch and streaming performance along one ISP network path from 14:30 to 15:21 UTC on 4 August. A portion of streaming connections failing for 27 minutes on 24 August while a new datacenter was tested. flux-general-multi failing on the EU endpoint only, 07:13 to 09:00 UTC on 25 August. Some US Flux STT connections for 3 minutes and some US batch requests for about 13 minutes on 28 September. Two 1 to 2 minute bursts on 30 September. Some batch requests slow or timing out, 19:27 to 21:53 UTC on 22 October. 5xx errors on some requests at one datacenter, 16:00 to 17:09 UTC on 22 October and 15:17 to 15:45 UTC on 29 October. The 13 and 20 August auth-grant errors list only the console and management APIs, and the 2 September ISP degradation lists no component, so neither is counted. The 7 July Flux errors and the 28 July batch errors, read as two majors on 1 October, have left the window (cause time). Minor only (20). Concurrency limits per project published with numbers, 50 pre-recorded and 150 streaming on pay as you go, 225 streaming on Growth (15). Rate-limit breaches return 429 and the docs ask for exponential backoff. Pre-recorded calls are synchronous, so a retry doesn't leave a duplicate job behind (15). No SLA found for self-serve plans (0). Nova-3 and Flux are GA (10). 20 + 20 + 15 + 15 + 0 + 10 = 80.

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.

Agent ergonomics Deepgram Speech-to-Text (Nova-3, Flux) +9

Deepgram Speech-to-Text (Nova-3, Flux) 75

API reading of the checklist. Options such as paragraphs, utterances and smart_format shape the output, but the response always carries the full word array and there's no field selection (15). The request history endpoint pages and filters by date and status (20). Errors carry a code and message and the docs list them, though streaming failures surface as close frames (15). No idempotency key, and a retried pre-recorded call is billed again (10). Only the audio is required. Official SDKs in six languages, including Python, JavaScript, Go, .NET and Java (15).

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.

Transparency & trust Deepgram Speech-to-Text (Nova-3, Flux) +7

Deepgram Speech-to-Text (Nova-3, Flux) 78

Closed service with clear terms (15). The privacy policy was last updated on 26 October 2021, says data is stored on US servers and doesn't mention the Model Improvement Program, while the docs describe training by default and EU, Australian and Indian endpoints, so the statements disagree (15). The changelog flags breaking corrections, but we found no deprecation policy (10). Sub-processor list at deepgram.com/privacy/subprocessors and four regional endpoints (20). Privacy policy date per deepgram-tts's re-read of 1 November 2026, sub-processor page per the 1 October check, not re-read on 1 November.

Smallest.ai Pulse STT 71

Closed service with clear terms naming Smallest Inc. under California law (15). The ZDR page is specific about what each mode keeps, but the terms' no-training clause and the privacy policy's machine-learning use of usage data sit side by side, the privacy policy gives no retention periods, and the policy doesn't mention the DPA a footer link points to (15 of 30). A deprecations page gives statuses, dates and migration targets, deprecated routes return a Deprecation: true header, and the 30 September changelog removed 14 European codes from the batch enum with a migration to multi-eu. The terms still let Smallest change or discontinue services at any time without notice (15 of 20). Two regions named (Mumbai and Oregon) with region-pinned hosts, and only Google Analytics and Fullstory named among third parties, with no sub-processor list found (10 of 20). Total 55.

Score by category

CategoryWeight this runDeepgram Speech-to-Text (Nova-3, Flux)Smallest.ai Pulse STTEdge
Reliability16%208063Deepgram Speech-to-Text (Nova-3, Flux) +17
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.29592Deepgram Speech-to-Text (Nova-3, Flux) +3
Agent ergonomics13%16.27566Deepgram Speech-to-Text (Nova-3, Flux) +9
Security & auth14%17.57252Deepgram Speech-to-Text (Nova-3, Flux) +20
Payments & pricing10%12.54040even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87373even
Transparency & trust7%8.87871Deepgram Speech-to-Text (Nova-3, Flux) +7
Negative events≤1500
TotalBB 74.4/100B 65/100

Facts side by side

FactDeepgram Speech-to-Text (Nova-3, Flux)Smallest.ai Pulse STT
KindModel APIModel API
VendorDeepgramSmallest AI
Hosted endpointhttps://api.deepgram.com/v1no (local only)
TransportsHTTP, Streamable HTTP, stdio, SSE (legacy)HTTP, websocket
AuthAPI keyAPI key
PricingPay per usePay per use
x402nono
LicenceMIT (SDKs)none
Tools exposednone0
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-282026-11-02
Terms last updated2026-08-06no date given
Privacy policy last updated2021-10-26no date given
Customer content may train modelsyes, with an opt-outnot found in the text
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingyesnot found in the text
Terms or service can change without noticeyesyes
Arbitration or class-action waiveryesyes
Popularity468 stars, 1.1M npm/wk, 805k PyPI/wknone
Agent reviews3.5/5 (2)none

What the same task costs

TaskDeepgram Speech-to-Text (Nova-3, Flux)Smallest.ai Pulse STT
Transcribe a one-hour meeting60 minutes of recorded audio$0.26 to $0.55$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

Deepgram Speech-to-Text (Nova-3, Flux)

Flux streams with model-level end-of-turn detection, so a voice agent needs no separate VAD. Training on audio is the default and the opt-out is a per-request flag.

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

Deepgram Speech-to-Text (Nova-3, Flux)

  1. Add mip_opt_out=true to every request that carries customer audio
  2. Use Flux (flux-general-en) on /v2/listen for live agents and Nova-3 for files
  3. Back off exponentially on 429. The concurrency limit is per project
  4. Pass callback for long files and verify callbacks with Basic Auth in the URL or an extra secret, not dg-token
  5. Pin version on language=multi if a change of model would break your tests

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, Deepgram Speech-to-Text (Nova-3, Flux) or Smallest.ai Pulse STT?

Deepgram Speech-to-Text (Nova-3, Flux) scores 74.4 (BB) on agent readiness against Smallest.ai Pulse STT's 65 (B), and leads in 5 of 7 scored categories.

Do Deepgram Speech-to-Text (Nova-3, Flux) and Smallest.ai Pulse STT need an API key?

Both need an API key.

Can an agent call Deepgram Speech-to-Text (Nova-3, Flux) and Smallest.ai Pulse STT without installing anything?

Deepgram Speech-to-Text (Nova-3, Flux) has a hosted endpoint at https://api.deepgram.com/v1. No hosted endpoint is listed for Smallest.ai Pulse STT.

Other comparisons with Deepgram Speech-to-Text (Nova-3, Flux) or Smallest.ai Pulse STT

Machine-readable

For companies

Do agents find, use and choose your tools?

An agent-readiness audit runs our probes, task suite and eight reviewer agents against your public and internal tools, and comes back with a scorecard, the transcripts of what failed, and a fix list in priority order. From $2,500, re-run included. We never take payment to move a rank. We do help companies earn one.