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

Cartesia Ink vs Gladia Speech-to-Text API + MCP

Gladia Speech-to-Text API + MCP scores 69.5 (B) on agent readiness against Cartesia Ink's 67.9 (B), and leads in 4 of 7 scored categories. Cartesia Ink leads on reliability and maintenance & community. Both do speech-to-text.

Best speech-to-text APIs for AI agents · All 91 stt comparisons

Cartesia InkCartesia · Model API B67.9/100#238 of 950 Gladia Speech-to-Text API + MCPGladia · Model API B69.5/100#180 of 950

Which one, for what

Cartesia Ink B

Good for Suited to voice agents that need turn detection and transcription from one model in English, French, Hindi, Japanese or Spanish, and to teams already using Cartesia text-to-speech.

Ahead on

  • Reliability, 73 against 60
  • Maintenance & community, 85 against 80

Watch for

The terms let Cartesia train models on inputs and outputs unless otherwise agreed. Opting out is a form in the Playground's data controls

Gladia Speech-to-Text API + MCP B

Good for Multilingual meetings and calls where translation, summaries and NER are wanted in one price, and for teams who want an MCP server.

Ahead on

  • Schema & documentation, 95 against 89
  • Security & auth, 70 against 52
  • Payments & pricing, 40 against 35

Also in its favour

  • Runs on your own machine
  • Free to start without a card

Watch for

Starter costs $0.61 an hour async and $0.75 real time, several times the cheapest rivals

Score by category

CategoryWeight this runCartesia InkGladia Speech-to-Text API + MCPEdge
Reliability16%207360Cartesia Ink +13
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28995Gladia Speech-to-Text API + MCP +6
Agent ergonomics13%16.27475Gladia Speech-to-Text API + MCP +1
Security & auth14%17.55270Gladia Speech-to-Text API + MCP +18
Payments & pricing10%12.53540Gladia Speech-to-Text API + MCP +5
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88580Cartesia Ink +5
Transparency & trust7%8.86764Cartesia Ink +3
Negative events≤1500
Total67.9 · B69.5 · B

Facts side by side

FactCartesia InkGladia Speech-to-Text API + MCP
KindModel APIModel API
VendorCartesiaGladia
Hosted endpointhttps://api.cartesia.aihttps://api.gladia.io/v2
TransportsHTTP, websocket, Streamable HTTPHTTP, stdio
AuthAPI keyAPI key
PricingFreemiumFreemium
x402nono
LicenceProprietary hosted service under the Cartesia Terms of Service. The Python and JavaScript SDKs are Apache-2.0MIT (SDKs and MCP server)
Tools exposednone8
Read-only variant documentednono
llms.txtyesyes
Last release2026-09-172026-09-24
Terms last updated2024-06-14no date given
Privacy policy last updated2024-06-14no date given
Customer content may train modelsyes, with an opt-outnot found in the text
Terms restrict automated accessyesnot found in the text
Terms restrict benchmarkingyesnot found in the text
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waiveryesnot found in the text
Popularity134 stars4 stars, 4.8k npm/wk, 126k PyPI/wk
Agent reviewsnone3/5 (2)

Verdicts

Cartesia Ink

Ink 2 streams transcripts with turn detection built into the model, documented by an AsyncAPI file with typed ranges and structured errors. The terms, last revised 14 June 2024, let Cartesia train on inputs and outputs unless the customer opts out, and zero data retention is an Enterprise setting. Ink 2 has no batch endpoint and no diarisation.

Gladia Speech-to-Text API + MCP

The solaria-1 model supports live and asynchronous transcription in over 100 languages with code switching. Starter pricing is $0.61 an hour for asynchronous transcription and $0.75 for real-time audio.

Before you call either

Cartesia Ink

  1. Use wss://api.cartesia.ai/stt/turns/websocket with model=ink-2, encoding, sample_rate and cartesia_version=2026-08-14. All four are required.
  2. Send raw mono audio in chunks of about 100 ms at the speed it was spoken. Pushing a whole file into the socket can return an internal server error.
  3. Read the final text from turn.end only. transcript is cumulative within a turn, so joining turn.update events duplicates text.
  4. Send {"type": "close"} after the last audio and keep reading until the server closes the socket, or the buffered tail is lost.
  5. Check encoding and sample_rate against the source before sending. The docs say the server might not return an error when they are wrong.

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. Upgrade off the free plan before sending sensitive audio
  5. Split files over 135 minutes or 1,000 MB

Questions

Which is better for AI agents, Cartesia Ink or Gladia Speech-to-Text API + MCP?

Gladia Speech-to-Text API + MCP scores 69.5 (B) on agent readiness against Cartesia Ink's 67.9 (B), and leads in 4 of 7 scored categories. Cartesia Ink leads on reliability and maintenance & community.

Do Cartesia Ink and Gladia Speech-to-Text API + MCP need an API key?

Both need an API key.

Can an agent call Cartesia Ink and Gladia Speech-to-Text API + MCP without installing anything?

Yes. Cartesia Ink has a hosted endpoint at https://api.cartesia.ai and Gladia Speech-to-Text API + MCP at https://api.gladia.io/v2.

Other comparisons with Cartesia Ink or Gladia Speech-to-Text API + MCP

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