Speech-to-text API

Send audio, poll the job, and read back segments with word timings and speaker labels as JSON, TXT or SRT. The language is detected automatically or set per request; the Oracle models also translate.

Get an API key Read the docs

Quickstart

Start a job, then read it back. Every parameter is listed in the API documentation.

curl https://app.kolwrite.com/transcribe \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"audio_url": "https://example.com/meeting.m4a",
       "model": "oracle",
       "language": "he",
       "include_diarization": true,
       "output_format": "json"}'

{"jobId": "34c63d45-4cb5-473b-bc60-25c175e69c57"}
curl https://app.kolwrite.com/transcribe/34c63d45-4cb5-473b-bc60-25c175e69c57 \
  -H "x-api-key: YOUR_API_KEY"

{
  "jobId": "34c63d45-4cb5-473b-bc60-25c175e69c57",
  "status": "COMPLETED",
  "result": {
    "language": "he",
    "segments": [
      {
        "start": 0.5,
        "end": 3.2,
        "speaker": "Speaker 1",
        "text": "שלום, נתחיל את הפגישה.",
        "words": [{"start": 0.5, "end": 0.8, "word": "שלום"}]
      }
    ]
  }
}

What the API returns

  • Word-level start and end times in JSON and SRT.
  • Speaker labels from diarization, or one label per physical audio channel.
  • Translation into another language on the Oracle models.
  • JSON, plain text or SRT, selected per request.
  • A webhook when the job finishes, or poll the job yourself.
  • Language detected automatically, or set per request.

Benchmarks

Accuracy on Google FLEURS and Mozilla CommonVoice. Higher is better.

Google FLEURS Accuracy (%)

Pricing

Credits per hour of audio, charged per job.

1 credit US$1.20

Model Credits/hour
Base 0.40
Oracle Mini 0.80
Oracle 1.20
Oracle Pro 1.40
Oracle Max 3.00
CoreLegacy 1.00
EdgeLegacy 1.20

Standard channel speaker separation is included. Overlapping-speech separation is billed at the selected model rate for the greater of the recording duration or the total detected speech time across its physical channels. Neither mode adds a diarization surcharge.

Model Comparison

Model options at a glance.

Model Credits/hour Summary Best for
Base 0.40 Low-cost transcription with word timestamps. Clear audio and high-volume jobs
Oracle Mini 0.80 Fast, economical Oracle tier. Drafts and high-throughput work
OracleFlagship 1.20 Production transcription and translation. Balanced quality, speed, and cost
Oracle Pro 1.40 Higher-quality Oracle tier. Demanding production audio
Oracle Max 3.00 Maximum-quality Oracle tier. Difficult, high-stakes audio
CoreLegacy 1.00 Fast legacy general-purpose model. Existing Core integrations
EdgeLegacy 1.20 Previous-generation high-accuracy model. Existing Edge integrations

Get an API key

Create an account, then generate a key on the API Keys page.

Get an API key Read the docs