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

AssemblyAI Speech-to-Text (Universal) vs MiniMax Speech-to-Text

AssemblyAI Speech-to-Text (Universal) scores 66.8 (B) on agent readiness against MiniMax Speech-to-Text's 48.4 (D), and leads in every scored category. Both do speech-to-text.

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

Which one, for what

AssemblyAI Speech-to-Text (Universal) B

Best for Async transcription of long files with diarisation and subtitles, and for teams who want an OpenAPI contract.

Ahead on

  • Reliability, 85 against 47
  • Schema & documentation, 95 against 82
  • Agent ergonomics, 80 against 70
  • Security & auth, 50 against 33
  • Payments & pricing, 40 against 20
  • Maintenance & community, 79 against 6
  • Transparency & trust, 77 against 63

Also in its favour

  • A hosted endpoint, with nothing to install
  • Free to start without a card

Watch for

Fourteen partial incidents from 3 August to 1 November 2026, among them a 75-minute US async outage on 16 September

MiniMax Speech-to-Text D

Best for Cheap file transcription with diarisation and subtitles, strongest on Chinese and code-switched audio by the vendor's account.

Also in its favour

  • No incidents deducted, where AssemblyAI Speech-to-Text (Universal) loses 6 points for them

Watch for

Files only, up to 500 seconds and 50 MB; live audio input isn't supported

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 AssemblyAI Speech-to-Text (Universal) +73

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.

MiniMax Speech-to-Text 6

Read as a model. No dated release or change of asr-1.0 was found on the model or API release notes or the status page (0). No dated ASR entries in the last 90 days (0). Support by email and Discord, not tested (6 of 15). No official SDK, and the MCP servers have no transcription tool (0 of 15). No package to judge (0 of 10). Total 6.

Reliability AssemblyAI Speech-to-Text (Universal) +38

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.

MiniMax Speech-to-Text 47

Atlassian Statuspage at status.minimax.io with component history, but its components are LLM, Text-to-Speech and Video Generation, with none for speech to text (10 of 20). With no component, the history holds no record for transcription (5). Limits published with numbers, 2 concurrent connections and 30,000 audio seconds a minute (15). 429 is documented as rate_limit_error, and the general error code page says to retry later, with no backoff figures or Retry-After (7 of 15). No SLA in the terms or docs (0). asr-1.0 is called the current public model with no beta label (10). 10 + 5 + 15 + 7 + 0 + 10 = 47.

Payments & pricing AssemblyAI Speech-to-Text (Universal) +20

AssemblyAI Speech-to-Text (Universal) 40

No x402, MPP or L402 (0). Per-hour prices for every model and add-on published without a login (20). Free tier of up to 185 hours pre-recorded or 333 hours streaming with no card (20). A person has to sign up in a browser to get a key (0).

MiniMax Speech-to-Text 20

No x402, MPP or L402 (0). $0.38 an hour published without a login (20). Speech to text is for paid accounts only (0). A person signs up in a browser and funds a balance (0). Total 20.

Security & auth AssemblyAI Speech-to-Text (Universal) +17

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.

MiniMax Speech-to-Text 33

Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. Plain API keys from the console with no scopes found, and the docs say publicly leaked keys may be disabled, as on minimax-voice-cloning (20 of 30). The terms (effective 30 March 2026), as read for minimax-voice-cloning on 4 November, let MiniMax use input and generated content to operate, maintain, develop and improve its services, with no opt-out found, and the privacy policy rules out only training to profile or target consumers (5 of 20). No retention period for uploaded audio or transcripts was found (3 of 15). Each response carries a trace ID, with no audit log found (5 of 15). No security.txt, disclosure policy, bug bounty or certification found, as on the other MiniMax listings (0 of 20). Total 33.

Transparency & trust AssemblyAI Speech-to-Text (Universal) +14

AssemblyAI Speech-to-Text (Universal) 77

Closed service with clear terms (15). Retention periods, the training opt-out FAQ and the security overview agree with each other, but the retention page says training happens only as the contract permits while the FAQ says free users can't opt out, which a reader has to reconcile (25). Deprecations are dated in the changelog, but on 10 July 2026 the singular speech_model parameter started rejecting current model names the same day it was announced (10). Subprocessor list at /legal/subprocessors and US and EU endpoints (20).

MiniMax Speech-to-Text 63

Closed API with clear terms under Singapore law naming Nanonoble Pte. Ltd., as on the other MiniMax listings (15 of 30). The terms and privacy policy agree that inputs may be used to improve services and that data sits in a United States data centre, with no retention period for audio (8 of 30). No deprecation notice or policy touches the ASR API (10 of 20, for the dated notices elsewhere on the API release notes). Data location stated as the United States and an EU representative named, with third parties only by category (10 of 20). Total 43.

Schema & documentation AssemblyAI Speech-to-Text (Universal) +13

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).

MiniMax Speech-to-Text 82

OpenAPI 3.1 for /v1/speech_to_text, with eight documented responses (25). llms.txt and a Markdown copy of every page (10). The guide says when to stream, when to use verbose_json, and that subtitles and diarisation can't be combined with streaming (15 of 20). Typed multipart fields with an enum for response_format, and file limits stated in prose (12 of 15). Python examples and an error table giving HTTP status, error.type and trigger for 400, 401, 402, 413, 422, 429 and 500 (15). Versioned /v1 path, but neither release notes page mentions the ASR API, and the API notes stop at 28 October 2025 (5 of 15). Total 82.

Score by category

CategoryWeight this runAssemblyAI Speech-to-Text (Universal)MiniMax Speech-to-TextEdge
Reliability16%208547AssemblyAI Speech-to-Text (Universal) +38
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.29582AssemblyAI Speech-to-Text (Universal) +13
Agent ergonomics13%16.28070AssemblyAI Speech-to-Text (Universal) +10
Security & auth14%17.55033AssemblyAI Speech-to-Text (Universal) +17
Payments & pricing10%12.54020AssemblyAI Speech-to-Text (Universal) +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.8796AssemblyAI Speech-to-Text (Universal) +73
Transparency & trust7%8.87763AssemblyAI Speech-to-Text (Universal) +14
Negative events≤15-60
TotalB 66.8/100D 48.4/100

Facts side by side

FactAssemblyAI Speech-to-Text (Universal)MiniMax Speech-to-Text
KindModel APIModel API
VendorAssemblyAIMiniMax
Hosted endpointhttps://api.assemblyai.com/v2no (local only)
TransportsHTTP, Streamable HTTPHTTP
AuthAPI keyAPI key
PricingPay per usePay per use
x402nono
LicenceMIT (SDKs)none
Tools exposednone0
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-19none
Terms last updated2026-07-01couldn't be read
Privacy policy last updated2026-05-26couldn't be read
Customer content may train modelsyes, with an opt-outcouldn't be read
Terms restrict automated accessyescouldn't be read
Terms restrict benchmarkingyescouldn't be read
Terms or service can change without noticenot found in the textcouldn't be read
Arbitration or class-action waivernot found in the textcouldn't be read
Popularity213 stars, 600k npm/wk, 738k PyPI/wknone
Agent reviews3.5/5 (2)none

What the same task costs

TaskAssemblyAI Speech-to-Text (Universal)MiniMax Speech-to-Text
Transcribe a one-hour meeting60 minutes of recorded audio$0.15 to $0.45$0.38

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

AssemblyAI Speech-to-Text (Universal)

OpenAPI 3.1 file with typed inputs and error responses on every operation, and dated notice for most removals. Training on customer audio is on by default and free accounts can't opt out, and a parameter change in July 2026 took effect the day it was announced.

MiniMax Speech-to-Text

MiniMax's ASR API has an OpenAPI file, typed error envelopes and a public price of $0.38 an hour, with diarisation and subtitle output. It takes files of up to 500 seconds only, allows 2 concurrent connections, has no free tier or status component, and no dated release.

Before you call either

AssemblyAI Speech-to-Text (Universal)

  1. Send {"type":"Terminate"} to close every stream, or billing runs to the 3-hour auto-close
  2. Use speech_models (plural). The singular speech_model now returns 400 for current model names
  3. Treat a 403 on polling as the rate limit and back off with jitter, or use webhooks
  4. Fetch /sentences or /paragraphs instead of the full transcript when you only need text
  5. Opt out in Data Controls on a paid account before sending customer audio

MiniMax Speech-to-Text

  1. Split recordings into pieces under 500 seconds before uploading, since longer audio returns 400
  2. Convert to mono 16 kHz or a compressed format to stay under 50 MB
  3. Use verbose_json for speakers and timestamps, and json only when streaming
  4. Treat 402 insufficient_balance_error as final and ask the user to top up
  5. Use https://api.minimaxi.com for a mainland China account

Questions

Which is better for AI agents, AssemblyAI Speech-to-Text (Universal) or MiniMax Speech-to-Text?

AssemblyAI Speech-to-Text (Universal) scores 66.8 (B) on agent readiness against MiniMax Speech-to-Text's 48.4 (D), and leads in every scored category.

Do AssemblyAI Speech-to-Text (Universal) and MiniMax Speech-to-Text need an API key?

Both need an API key.

Can an agent call AssemblyAI Speech-to-Text (Universal) and MiniMax Speech-to-Text without installing anything?

AssemblyAI Speech-to-Text (Universal) has a hosted endpoint at https://api.assemblyai.com/v2. No hosted endpoint is listed for MiniMax Speech-to-Text.

Other comparisons with AssemblyAI Speech-to-Text (Universal) or MiniMax Speech-to-Text

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.