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APIsSpeech to Text

REST

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Speech to Text API

This API transcribes speech to text in multiple Indian languages and English. Supports transcription for interactive applications.

Available Options:

  • REST API (Current Endpoint): For quick responses under 30 seconds with immediate results
  • Batch API: For longer audio files, Follow This Documentation
    • Supports diarization (speaker identification)

Note:

  • Pricing differs for REST and Batch APIs
  • Diarization is only available in Batch API with separate pricing
  • Please refer to here for detailed pricing information

Authentication

api-subscription-keystring
API Key authentication via header

Request

This endpoint expects a multipart form containing a file.
filefileRequired

The audio file to transcribe. Supported formats include WAV, MP3, AAC, AIFF, OGG, OPUS, FLAC, MP4/M4A, AMR, WMA, WebM, and PCM formats. The API automatically detects most codec formats, but for PCM files (pcm_s16le, pcm_l16, pcm_raw), you must specify the input_audio_codec parameter. PCM files are supported only at 16kHz sample rate. The API works best with audio files sampled at 16kHz. If the audio contains multiple channels, they will be merged into a single channel.

modelenumOptional

Specifies the model to use for speech-to-text conversion.

  • saaras:v4 (default, recommended, latest): Flexible output formats across all modes (transcribe, translate, verbatim, translit, codemix), supporting Global + Indian English and 22 Indic languages.

  • saaras:v3: State-of-the-art model with flexible output formats. Supports multiple modes via the mode parameter: transcribe, translate, verbatim, translit, codemix.

Allowed values:
modeenum or nullOptionalDefaults to transcribe

Mode of operation. Only applicable when using saaras:v3 model.

Example audio: 'मेरा फोन नंबर है 9840950950'

  • transcribe (default): Standard transcription in the original language with proper formatting and number normalization.

    • Output: मेरा फोन नंबर है 9840950950

  • translate: Translates speech from any supported Indic language to English.

    • Output: My phone number is 9840950950

  • verbatim: Exact word-for-word transcription without normalization, preserving filler words and spoken numbers as-is.

    • Output: मेरा फोन नंबर है नौ आठ चार zero नौ पांच zero नौ पांच zero

  • translit: Romanization - Transliterates speech to Latin/Roman script only.

    • Output: mera phone number hai 9840950950

  • codemix: Code-mixed text with English words in English and Indic words in native script.

    • Output: मेरा phone number है 9840950950
Allowed values:
language_codeenumOptional

Specifies the language of the input audio in BCP-47 format.

Available Options:

  • unknown: Use when the language is not known; the API will auto-detect.
  • hi-IN: Hindi
  • bn-IN: Bengali
  • kn-IN: Kannada
  • ml-IN: Malayalam
  • mr-IN: Marathi
  • od-IN: Odia
  • pa-IN: Punjabi
  • ta-IN: Tamil
  • te-IN: Telugu
  • en-IN: English
  • gu-IN: Gujarati
  • as-IN: Assamese
  • ur-IN: Urdu
  • ne-IN: Nepali
  • kok-IN: Konkani
  • ks-IN: Kashmiri
  • sd-IN: Sindhi
  • sa-IN: Sanskrit
  • sat-IN: Santali
  • mni-IN: Manipuri
  • brx-IN: Bodo
  • mai-IN: Maithili
  • doi-IN: Dogri
with_timestampsbooleanOptionalDefaults to false

Enables chunk-level timestamps in the response. If set to true, the response includes a timestamps object with words, start_time_seconds, and end_time_seconds (each entry covers a sentence or phrase, not an individual word).

Note: Word-level timestamps are not supported. Speaker diarization is not supported on the REST API; use the Batch API for diarized, chunk-level timestamps.

input_audio_codecenumOptional

Input Audio codec/format of the input file. PCM files are supported only at 16kHz sample rate.

keytermslist of strings or nullOptional

List of up to 50 domain-specific terms (names, places, brands, technical terms) to bias recognition toward. Each keyterm can contain up to 64 characters. Put phrases such as New Delhi in one list item; do not send comma-separated terms in one string. Keyterms bias recognition — they do not guarantee that a term will appear in the transcript. Only supported with model=saaras:v4. Sent as a JSON-encoded array in one multipart form field, e.g. keyterms=["Sarvam","New Delhi","Vistaar"]. Do not use the older keyterm or hotwords fields.

Response

Successful Response
request_idstring or null
transcriptstring
The transcribed text from the provided audio file.
language_codestring or null

This will return the BCP-47 code of language spoken in the input. If multiple languages are detected, this will return language code of most predominant spoken language. If no language is detected, this will be null

timestampsobject or nullOptional

Chunk-level timestamps for the transcribed text (sentence/phrase segments, not individual words). Present only when with_timestamps is true; omitted otherwise.

language_probabilitydouble or nullOptional

Float value (0.0 to 1.0) indicating confidence in the detected language. Present when language_code is omitted or set to unknown; omitted (or null) when a specific language code is provided.

Errors

400
Bad Request Error
403
Forbidden Error
422
Unprocessable Entity Error
429
Too Many Requests Error
500
Internal Server Error
503
Service Unavailable Error