Speech-to-Text Service

Convert spoken audio into accurate transcripts using flexible endpoints. Use /v1/audio/transcribe for streaming SSE results, /v1/audio/transcribe_ws for real-time WebSocket streaming, /v1/audio/transcribe_file + GET /v1/audio/transcribe_status/{request_id} for web-only batch jobs up to 10 minutes, /v1/audio/transcribe/diarize + GET /v1/audio/transcribe/diarize/status/{job_id} for speaker-labeled transcription up to 30 minutes, and GET /v1/audio/transcribe/config to inspect supported formats and defaults before uploading.

Need an API Key? If you don't have an API key yet, you can create one here: https://playground.induslabs.io/register

Available languages

Englishen
Spanishes
Frenchfr
Germande
Italianit
Portuguesept
Russianru
Japaneseja
Koreanko
Chinesezh
Arabicar
Hindihi
Turkishtr
Polishpl
Dutchnl
Swedishsv
Danishda
Norwegianno
Finnishfi
Czechcs
Slovaksk
Hungarianhu
Romanianro
Bulgarianbg
Croatianhr
Sloveniansl
Estonianet
Latvianlv
Lithuanianlt
Maltesemt
Irishga
Welshcy
Icelandicis
Macedonianmk
Albaniansq
Azerbaijaniaz
Kazakhkk
Kyrgyzky
Uzbekuz
Tajiktg
Amharicam
Burmesemy
Khmerkm
Laolo
Sinhalasi
Nepaline
Bengalibn
Assameseas
Odiaor
Punjabipa
Gujaratigu
Tamilta
Telugute
Kannadakn
Malayalamml
Thaith
Vietnamesevi
Indonesianid
Malayms
Filipino/Tagalogtl

Screenshot: where to find your API key. Create one at playground.induslabs.io/register

POST/v1/audio/transcribe

Transcribe Audio (Streaming)

This endpoint is used to transcribe audio files into text with streaming results via Server-Sent Events (SSE).

Functionality

Accepts an audio file and returns real-time transcription results.
Outputs partial, chunk-level, and final transcripts as the audio is processed.
Suitable for low-latency transcription where results are streamed back continuously.

Form Fields

Name	Type	Default	Description
`file`	file	required	Audio file to transcribe.
`api_key`	string	required	Authentication API key.
`language`	string	-	Language code (e.g., "en", "hi") for forced detection.
`chunk_length_s`	number	-	Length of each chunk in seconds (1–30).
`stride_s`	number	-	Stride between chunks in seconds (1–29).
`overlap_words`	integer	-	Number of overlapping words for context handling (0–20).

Outputs

Status	Type	Description
`200 OK`	text/event-stream	Returns transcription results in JSON (streamed via SSE).
`422 Validation Error`	application/json	Validation failure. Inspect detail array.

200 OK (SSE stream)

data: {"type": "partial", "word": "यह", "provisional": true, "chunk_start": 0.0, "chunk_end": 3.413375, "chunk_index": 1, "total_chunks": 1}

data: {"type": "partial", "word": "एक", "provisional": true, "chunk_start": 0.0, "chunk_end": 3.413375, "chunk_index": 1, "total_chunks": 1}

data: {"type": "partial", "word": "टेस्ट", "provisional": true, "chunk_start": 0.0, "chunk_end": 3.413375, "chunk_index": 1, "total_chunks": 1}

data: {"type": "chunk_final", "text": "यह एक टेस्ट है, भाषन से पाट रूपांतरन का परिच्छन।", "chunk_start": 0.0, "chunk_end": 3.413375, "chunk_index": 1, "total_chunks": 1}

data: {"type": "final", "text": "यह एक टेस्ट है, भाषन से पाट रूपांतरन का परिच्छन।", "audio_duration_seconds": 3.413375, "processing_time_seconds": 1.44447922706604, "first_token_time_seconds": 0.136627197265625, "language_detected": "hi", "request_id": "df3a5974-6b24-4b15-a9d9-7c9df9513306"}

200 OK (Config)

{
  "model_id": "openai/whisper-large-v3",
  "supported_formats": ["wav", "mp3", "mp4", "m4a", "flac", "ogg"],
  "max_file_size_mb": 25,
  "hindi_model": {
    "enabled": true,
    "model_id": null
  },
  "defaults": {
    "chunk_length_s": 6.0,
    "stride_s": 5.9,
    "overlap_words": 7
  },
  "limits": {
    "chunk_length_range": [1.0, 30.0],
    "stride_range": [1.0, 29.0],
    "overlap_words_range": [0, 20],
    "timeout_seconds": 30
  },
  "supported_languages": [
    "en", "es", "fr", "de", "it", "pt", "ru", "ja", "ko", "zh",
    "ar", "hi", "tr", "pl", "nl", "sv", "da", "no", "fi", "cs",
    "sk", "hu", "ro", "bg", "hr", "sl", "et", "lv", "lt", "mt",
    "ga", "cy", "is", "mk", "sq", "az", "kk", "ky", "uz", "tg",
    "am", "my", "km", "lo", "si", "ne", "bn", "as", "or", "pa",
    "gu", "ta", "te", "kn", "ml", "th", "vi", "id", "ms", "tl"
  ],
  "output_formats": {
    "streaming": "Server-Sent Events (SSE) with real-time partial results",
    "file": "Complete JSON response with final transcript"
  },
  "credit_system": {
    "unit": "1 credit = 1 minute of audio",
    "billing": "Based on actual audio duration, not processing time"
  }
}

WS/v1/audio/transcribe_ws

WebSocket Streaming Transcription

Real-time STT via WebSocket. Supports bidirectional streaming for live audio input.

Key Features

Persistent Connection: Maintains open WebSocket for continuous audio streaming.
Real-time Results: Receives transcription segments as audio is processed.
Low Latency: Optimized for live microphone input and voice applications.
Segment Callbacks: Provides word-level and segment-level results via callbacks.
Bidirectional: Sends audio chunks and receives transcriptions simultaneously.
Noise Cancellation: Optional server-side denoising before inference.

WebSocket Connection

Connect to: wss://voice.induslabs.io/v1/audio/transcribe_ws

Unlike REST endpoints, WebSocket maintains a persistent bidirectional connection for real-time streaming.

Available Models

indus-stt-v1: Default model that supports all languages.
indus-stt-hi-en: Specialized model for Hindi and English with real-time streaming input/output and very low processing time.

WebSocket Message Flow

Message	Type	Order	Description
`URL Query Params`	URL	connection	Pass api_key, model, language, streaming as URL query parameters when connecting.
`Audio Chunks`	binary	continuous	Raw audio data sent as binary WebSocket frames (recommended: 4096 bytes per chunk).
`End Signal`	binary	last	Send b"__END__" to signal audio stream completion.

Configuration Parameters

Name	Type	Default	Description
`api_key`	string	required	Authentication API key passed in URL query string.
`model`	string	indus-stt-hi-en	Model to use (e.g., "indus-stt-hi-en").
`language`	string	-	Language name or ISO code (e.g., "english", "hindi", "en", "hi").
`streaming`	string	"true"	Use "true" for streaming mode (interim results), "false" for non-streaming.
`noise_cancellation`	string	"false"	Use "true" to enable noise cancellation for cleaner audio in noisy environments. Filters low-frequency rumble, high-frequency hiss, and ambient background noise to reduce hallucinations and improve accuracy.

Outputs

Status	Type	Description
`chunk_interim`	JSON	Interim transcription result during processing (when streaming="true").
`chunk_final`	JSON	Final transcription for a processed audio chunk.
`final`	JSON	Complete transcription with full text after all chunks processed.
`error`	JSON	Error message if processing fails.

Chunk Interim Response

{
  "type": "chunk_interim",
  "text": "यह एक टेस्ट है"
}

Chunk Final Response

{
  "type": "chunk_final",
  "text": "यह एक टेस्ट है, भाषन से पाट रूपांतरन का परिच्छन।",
  "chunk_index": 1,
  "total_chunks": 1
}

Final Response

{
  "type": "final",
  "text": "यह एक टेस्ट है, भाषन से पाट रूपांतरन का परिच्छन।",
  "audio_duration_seconds": 3.413375,
  "language_detected": "hi",
  "request_id": "df3a5974-6b24-4b15-a9d9-7c9df9513306"
}

Error Response

{
  "type": "error",
  "message": "Invalid API key",
  "code": "AUTH_ERROR"
}

POST/v1/audio/transcribe_file

Transcribe Audio File (Batch Async)

Launches background transcription for files up to 10 minutes and immediately returns a request_id to poll later.

Functionality

Designed for long recordings up to 10 minutes (600 seconds).
Returns immediately so your UI can poll the status endpoint or notify the user.
Available via REST on the web — SDK helpers are not yet available.
Supports optional noise cancellation before inference begins.

Form Fields

Name	Type	Default	Description
`file`	file	required	Audio file up to 10 minutes (600 seconds).
`api_key`	string	required	Authentication API key.
`model`	string	"default"	Use "default", "indus-stt-v1", "hi-en", or "indus-stt-hi-en".
`language`	string	-	Language hint (ISO code or name).
`noise_cancellation`	boolean	false	Enable server-side denoising before inference.

Outputs

Status	Type	Description
`202 Accepted`	application/json	Returns request_id, duration, estimated_time, and status_url for polling.
`400 Bad Request`	application/json	Audio rejected (e.g., longer than 10 minutes or invalid format).
`401 / 402`	application/json	Authentication failure or insufficient credits.

202 Accepted (Batch Upload)

{
  "request_id": "13c8b15a-59f9-4cda-a3bb-3bf06f5e2c9b",
  "status": "processing",
  "message": "File uploaded successfully. Processing in background.",
  "duration": 126.42,
  "estimated_time": 18.96,
  "status_url": "/v1/audio/transcribe_status/13c8b15a-59f9-4cda-a3bb-3bf06f5e2c9b",
  "poll_interval": 5
}

GET/v1/audio/transcribe_status/{request_id}

Get Batch Transcription Status

Polls the progress of a batch job created by /v1/audio/transcribe_file and returns the final transcript when completed.

Functionality

Call every poll_interval seconds until the job reports completed or failed.
Completed responses include full text, segments, word-level timestamps (if available), and processing metrics.
Failed jobs return an error string so that you can surface actionable feedback to users.

Form Fields

Name	Type	Default	Description
`request_id`	path	required	Identifier returned from /v1/audio/transcribe_file.
`api_key`	string (query)	required	Same key used when creating the job.

Outputs

Status	Type	Description
`200 OK`	application/json	Current status plus transcript, segments, and metrics when completed.
`404 Not Found`	application/json	Unknown or expired request_id.
`500 Internal Server Error`	application/json	Job failed; see error field for details.

200 OK (Batch Status)

{
  "request_id": "13c8b15a-59f9-4cda-a3bb-3bf06f5e2c9b",
  "status": "completed",
  "progress_percentage": 100,
  "progress": "3/3",
  "text": "Final transcription text...",
  "segments": [
    {"text": "segment text", "start": 0, "end": 12.5}
  ],
  "processing_time": 98.11,
  "model": "indus-stt-v1"
}

POST/v1/audio/transcribe/diarize

Diarize + Transcribe (Async)

Uploads audio for speaker diarization and per-speaker transcription, returning a job_id for polling.

Functionality

Runs speaker diarization before transcription to label speakers.
Supports files up to 30 minutes; processing occurs in the background.
Use config_json to tune language, noise_cancellation, padding, and concurrency parameters.
Returns an estimated_time and status_url so clients can poll without blocking.

Form Fields

Name	Type	Default	Description
`file`	file	required	Audio file to diarize (max 30 minutes).
`api_key`	string	required	Authentication API key.
`config_json`	string	"{}"	Optional JSON string to tune language, models, padding, and concurrency.

Outputs

Status	Type	Description
`200 OK`	application/json	Returns job_id, estimated_time, and status_url for polling diarization results.
`400 Bad Request`	application/json	Invalid audio, malformed config_json, or duration beyond 30 minutes.
`401 / 402`	application/json	Authentication failure or insufficient credits.
`503 Service Unavailable`	application/json	Credit service unavailable.

200 OK (Diarization Upload)

{
  "job_id": "7a5f2f0e4c8d4b2ab6d2c5d0fdc4b5e0",
  "status": "processing",
  "message": "File uploaded successfully. Processing in background.",
  "duration": 312.44,
  "estimated_time": 93.73,
  "status_url": "/v1/audio/transcribe/diarize/status/7a5f2f0e4c8d4b2ab6d2c5d0fdc4b5e0",
  "poll_interval": 5
}

GET/v1/audio/transcribe/diarize/status/{job_id}

Get Diarization Status

Polls the progress of a diarization + transcription job created by /v1/audio/transcribe/diarize.

Functionality

Poll every poll_interval seconds until status is completed or failed.
Completed responses return per-speaker utterances with start/end timestamps and transcript text.
Failed jobs include an error string so you can surface actionable feedback.

Form Fields

Name	Type	Default	Description
`job_id`	path	required	Identifier returned from /v1/audio/transcribe/diarize.
`api_key`	string (query)	required	Same key used when creating the job.

Outputs

Status	Type	Description
`200 OK`	application/json	Current diarization status plus speaker-labeled results when completed.
`404 Not Found`	application/json	Unknown or expired job_id.
`401 Unauthorized`	application/json	Invalid API key.
`503 Service Unavailable`	application/json	Credit service unavailable.

200 OK (Diarization Status)

{
  "job_id": "7a5f2f0e4c8d4b2ab6d2c5d0fdc4b5e0",
  "status": "completed",
  "results": [
    {
      "utterance_index": 1,
      "start_sec": 0.0,
      "end_sec": 14.2,
      "duration_sec": 14.2,
      "speaker": "speaker_0",
      "endpoint": "transcribe_file",
      "text": "Welcome everyone, let's review the agenda.",
      "status": "completed"
    },
    {
      "utterance_index": 2,
      "start_sec": 14.2,
      "end_sec": 29.8,
      "duration_sec": 15.6,
      "speaker": "speaker_1",
      "endpoint": "transcribe_ws",
      "text": "I will cover the launch metrics next.",
      "status": "completed"
    }
  ],
  "processing_time": 108.51,
  "model": "diarization"
}

GET/v1/audio/transcribe/config

Retrieve Transcription Configuration

Fetch default parameters, limits, and supported formats before sending audio for transcription.

Functionality

Provides current defaults for chunk sizing, stride, and overlap handling.
Lists accepted media formats and the maximum upload size in megabytes.
Use these values to validate client-side settings and avoid failed uploads.

Outputs

Status	Type	Description
`200 OK`	application/json	Returns defaults, limits, and supported languages/formats for the STT service.
`422 Validation Error`	application/json	Validation failure. Inspect detail array.

422 Validation Error

{
  "detail": [
    {
      "loc": ["string", 0],
      "msg": "string",
      "type": "string"
    }
  ]
}

200 OK (Config)

{
  "model_id": "openai/whisper-large-v3",
  "supported_formats": ["wav", "mp3", "mp4", "m4a", "flac", "ogg"],
  "max_file_size_mb": 25,
  "hindi_model": {
    "enabled": true,
    "model_id": null
  },
  "defaults": {
    "chunk_length_s": 6.0,
    "stride_s": 5.9,
    "overlap_words": 7
  },
  "limits": {
    "chunk_length_range": [1.0, 30.0],
    "stride_range": [1.0, 29.0],
    "overlap_words_range": [0, 20],
    "timeout_seconds": 30
  },
  "supported_languages": [
    "en", "es", "fr", "de", "it", "pt", "ru", "ja", "ko", "zh",
    "ar", "hi", "tr", "pl", "nl", "sv", "da", "no", "fi", "cs",
    "sk", "hu", "ro", "bg", "hr", "sl", "et", "lv", "lt", "mt",
    "ga", "cy", "is", "mk", "sq", "az", "kk", "ky", "uz", "tg",
    "am", "my", "km", "lo", "si", "ne", "bn", "as", "or", "pa",
    "gu", "ta", "te", "kn", "ml", "th", "vi", "id", "ms", "tl"
  ],
  "output_formats": {
    "streaming": "Server-Sent Events (SSE) with real-time partial results",
    "file": "Complete JSON response with final transcript"
  },
  "credit_system": {
    "unit": "1 credit = 1 minute of audio",
    "billing": "Based on actual audio duration, not processing time"
  }
}

Quick Integration

Sample requests to get transcription running in minutes.

API EndpointLanguage

import requests

url = "https://voice.induslabs.io/v1/audio/transcribe"
with open("audio.mp3", "rb") as audio_file:
    files = {"file": ("audio.mp3", audio_file, "audio/mpeg")}
    data = {
        "api_key": "YOUR_API_KEY",
        "language": "en"
    }
    with requests.post(url, files=files, data=data, stream=True, timeout=30) as response:
        response.raise_for_status()
        for line in response.iter_lines():
            if not line:
                continue
            print(line.decode("utf-8"))