APIbenchmarks

Category report · 8 providers evaluated

Best Speech-to-Text APIs

Speech-to-Text APIs convert audio into text, spanning batch (async file) and real-time streaming transcription, with add-ons like speaker diarization, translation, and PII redaction. The category splits into focused voice-AI specialists (Deepgram, AssemblyAI, Speechmatics, Gladia, Rev AI) optimized for accuracy, latency, and generous self-serve free tiers, versus hyperscaler platforms (Google, AWS) and the model-API generalist (OpenAI Whisper) that ride massive infrastructure but offer thinner DX and stingier free tiers. Compare on documentation/DX quality, reliability and proven scale, SDK breadth and ecosystem, and how fast a developer or AI agent can self-serve a working key against transparent public pricing.

Deepgram logo
Highest rated
Deepgram

Real-time streaming STT for voice agents

87.5
ABI
A
VerdictWhat is the best speech-to-text API?The short answer, plus which provider wins on each axis.Read the verdict →

What is the best Speech-to-Text API?

#ProviderDocumentationReliabilityEcosystemAccessibilityABIFree
1Deepgram logoDeepgramDeepgram9084829587.5AYes
2AssemblyAI logoAssemblyAIAssemblyAI9282839086.9AYes
3OpenAI Whisper / GPT-4o Transcribe logoOpenAI Whisper / GPT-4o TranscribeOpenAI8580888283.9BNo
4Google Cloud Speech-to-Text logoGoogle Cloud Speech-to-TextGoogle7892856881.3BYes
5Amazon Transcribe logoAmazon TranscribeAWS7493846278.9BYes
6Speechmatics logoSpeechmaticsSpeechmatics7680688476.6BYes
7Gladia logoGladiaGladia7870628874.0CYes
8Rev AI logoRev AIRev7474608572.7CYes

Table 1. Best Speech-to-Text APIs ranked by the APIbenchmarks Index. Specification columns are vendor-stated; ABI is computed per the published methodology.

Composite scores

Deepgram
87.5
AssemblyAI
86.9
OpenAI Whisper / GPT-4o Transcribe
83.9
Google Cloud Speech-to-Text
81.3
Amazon Transcribe
78.9
Speechmatics
76.6
Gladia
74.0
Rev AI
72.7
Scale 0–100. Highest in category: 87.5.

Figure 1. APIbenchmarks Index for Speech-to-Text APIs, bar length proportional to composite score; colour encodes letter grade.

Provider scorecards

Deepgram logo
1. DeepgramAABI 87.5 · Excellent

Voice-AI specialist with the Nova-3 and Flux models, known for sub-300ms streaming latency and a developer-first console.

Documentation & DX
90
Reliability
84
Ecosystem & SDKs
82
Accessibility
95
AssemblyAI logo
2. AssemblyAIAABI 86.9 · Excellent

Research-driven STT with the Universal and Slam-1 models and a deep audio-intelligence add-on stack (sentiment, topics, LeMUR LLM).

Documentation & DX
92
Reliability
82
Ecosystem & SDKs
83
Accessibility
90
OpenAI Whisper / GPT-4o Transcribe logo
3. OpenAI Whisper / GPT-4o TranscribeBABI 83.9 · Strong

Transcription endpoints (whisper-1, gpt-4o-transcribe, gpt-4o-mini-transcribe) bundled into the broader OpenAI API; simple flat per-minute pricing, no STT-specific free tier.

Documentation & DX
85
Reliability
80
Ecosystem & SDKs
88
Accessibility
82
Google Cloud Speech-to-Text logo
4. Google Cloud Speech-to-TextBABI 81.3 · Strong

Hyperscaler STT (Chirp models) with 125+ languages, contractual enterprise SLAs and GCP-wide infrastructure, but heavier console onboarding.

Documentation & DX
78
Reliability
92
Ecosystem & SDKs
85
Accessibility
68
Amazon Transcribe logo
5. Amazon TranscribeBABI 78.9 · Strong

AWS-native STT with volume tiering, deep IAM/S3 integration and proven hyperscaler reliability; powerful but verbose AWS-style docs and console.

Documentation & DX
74
Reliability
93
Ecosystem & SDKs
84
Accessibility
62
Speechmatics logo
6. SpeechmaticsBABI 76.6 · Strong

UK-based accuracy and multilingual specialist (55+ languages, strong accent coverage) with batch, real-time, and on-prem deployment options.

Documentation & DX
76
Reliability
80
Ecosystem & SDKs
68
Accessibility
84
Gladia logo
7. GladiaCABI 74.0 · Solid

European audio-infrastructure challenger wrapping Whisper-grade accuracy with all features (diarization, translation, code-switching) included at every tier.

Documentation & DX
78
Reliability
70
Ecosystem & SDKs
62
Accessibility
88
Rev AI logo
8. Rev AICABI 72.7 · Solid

STT arm of transcription company Rev, offering the Reverb and Whisper models plus optional human transcription; solid but a narrower SDK set.

Documentation & DX
74
Reliability
74
Ecosystem & SDKs
60
Accessibility
85

Frequently asked questions

What is the best Speech-to-Text API?
By the APIbenchmarks Index, Deepgram rates highest (ABI 87.5, grade A). Real-time streaming STT for voice agents The ABI weights documentation, reliability, ecosystem, and accessibility; price is reported separately, so the right pick still depends on your budget and workload.
Which speech-to-text APIs have a free tier?
Deepgram, AssemblyAI, Google Cloud Speech-to-Text, Amazon Transcribe, Speechmatics, Gladia, Rev AI offer a free tier or trial credits.
How is the APIbenchmarks Index calculated?
The ABI is a weighted composite of four dimensions scored on absolute reference scales: documentation & DX (30%), reliability (25%), ecosystem & SDKs (25%), and accessibility (20%). Price is excluded from the composite because price units are not comparable across categories. The full formula is on the methodology page.

Popular comparisons

Deepgram vs AssemblyAIDeepgram vs OpenAI Whisper / GPT-4o TranscribeDeepgram vs Google Cloud Speech-to-TextAssemblyAI vs OpenAI Whisper / GPT-4o TranscribeAssemblyAI vs Google Cloud Speech-to-TextOpenAI Whisper / GPT-4o Transcribe vs Google Cloud Speech-to-Text

References

  1. https://deepgram.com/pricing
  2. https://deepgram.com/learn/introducing-nova-3-speech-to-text-api
  3. https://developers.deepgram.com/sdks/sdk-features
  4. https://artificialanalysis.ai/speech-to-text/models/deepgram
  5. https://www.g2.com/products/deepgram/reviews
  6. https://status.deepgram.com/
  7. https://deepgram.com/dedicated
  8. https://developers.deepgram.com/docs/keyterm
  9. https://diyai.io/ai-tools/speech-to-text/reviews/deepgram-ai-review/
  10. https://www.assemblyai.com/pricing
  11. https://www.assemblyai.com/blog/introducing-universal-streaming
  12. https://www.assemblyai.com/blog/comparing-universal-2-and-openai-whisper
  13. https://www.assemblyai.com/docs/faq/what-is-your-api-uptime-sla
  14. https://status.assemblyai.com/
  15. https://www.g2.com/products/assemblyai-speech-to-text-api/reviews
  16. https://www.coval.ai/blog/best-speech-to-text-providers-in-2026-independent-benchmarks-and-how-to-choose/
  17. https://brasstranscripts.com/blog/assemblyai-pricing-per-minute-2025-real-costs
  18. https://www.assemblyai.com/features/speaker-diarization
  19. https://openai.com/index/introducing-our-next-generation-audio-models/
  20. https://developers.openai.com/api/docs/guides/speech-to-text
  21. https://developers.openai.com/api/docs/pricing
  22. https://platform.openai.com/docs/models/gpt-4o-transcribe-diarize
  23. https://openai.com/index/whisper/
  24. https://www.promptt.dev/blog/whisper-1-vs-gpt-4o-transcribe-full-comparison-2025
  25. https://simonw.substack.com/p/new-audio-models-from-openai-but
  26. https://community.openai.com/t/introducing-gpt-4o-transcribe-diarize-now-available-in-the-audio-api/1362933
  27. https://cloud.google.com/speech-to-text/pricing
  28. https://cloud.google.com/speech-to-text/sla
  29. https://docs.cloud.google.com/speech-to-text/docs/models/chirp-3
  30. https://cloud.google.com/blog/products/ai-machine-learning/google-cloud-speech-to-text-v2-api
  31. https://cloud.google.com/speech-to-text/v2/docs/libraries
  32. https://deepgram.com/learn/deepgram-vs-google-speech-to-text-comparison
  33. https://www.g2.com/products/google-cloud-speech-to-text/reviews
  34. https://id.cloud-ace.com/resources/cloud-speech-to-text-v2-api-and-chirp-are-now-generally-available-with-new-lower-pricing-tier
  35. https://brasstranscripts.com/blog/google-cloud-speech-to-text-pricing-2025-gcp-integration-costs
  36. https://aws.amazon.com/transcribe/pricing/
  37. https://aws.amazon.com/transcribe/features/
  38. https://aws.amazon.com/ai/services/language-sla/
  39. https://artificialanalysis.ai/speech-to-text/models/aws
  40. https://www.peerspot.com/products/amazon-transcribe-reviews
  41. https://www.g2.com/products/amazon-transcribe/reviews
  42. https://universitytranscriptions.co.uk/word-error-rates-wer-for-ai-transcription-what-do-they-tell-us/
  43. https://docs.aws.amazon.com/transcribe/latest/dg/diarization.html
  44. https://brasstranscripts.com/blog/aws-transcribe-pricing-per-minute-2025-better-alternative
  45. https://www.speechmatics.com/pricing
  46. https://docs.speechmatics.com/
  47. https://github.com/speechmatics/speechmatics-python-sdk
  48. https://www.speechmatics.com/how-we-compare/deepgram-alternative
  49. https://www.g2.com/products/speechmatics/reviews
  50. https://www.g2.com/products/speechmatics/reviews?qs=pros-and-cons
  51. https://status.speechmatics.com/
  52. https://www.gartner.com/reviews/product/speechmatics-asr
  53. https://docs.speechmatics.com/features-other/translation
  54. https://www.gladia.io/pricing
  55. https://www.gladia.io/blog/solaria-3-speech-to-text-model-for-european-languages
  56. https://www.gladia.io/blog/introducing-solaria-the-first-truly-universal-speech-to-text-model
  57. https://www.g2.com/products/gladia/reviews
  58. https://techcrunch.com/2024/10/15/gladia-believes-real-time-processing-is-the-next-frontier-of-audio-transcription-apis/
  59. https://sifted.eu/articles/gladia-raise-ai-france-news
  60. https://www.gladia.io/blog/measuring-latency-in-stt
  61. https://aws.amazon.com/marketplace/reviews/reviews-list/prodview-hrjyzqt2qpexe
  62. https://www.capterra.com/p/10019495/Gladia/
  63. https://www.rev.ai/pricing
  64. https://docs.rev.ai/api/features
  65. https://docs.rev.ai/sdk
  66. https://github.com/revdotcom
  67. https://www.rev.com/resources/asr-benchmark-report
  68. https://www.rev.com/blog/google-speech-recognition-api-vs-rev-ai-api
  69. https://www.rev.com/resources/microsoft-azure-speech-recognition-vs-rev-ai-speech-to-text-api
  70. https://www.g2.com/products/rev-ai-speech-to-text-api/reviews
  71. https://www.assemblyai.com/blog/assemblyai-vs-rev-ai