> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cartesia.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Speech-to-Text (Batch)
> Transcribes audio files into text using Cartesia's Speech-to-Text API.
Upload an audio file and receive a complete transcription response. Supports arbitrarily long audio files with automatic intelligent chunking for longer audio.
**Supported audio formats:** flac, m4a, mp3, mp4, mpeg, mpga, oga, ogg, wav, webm
**Response format:** Returns JSON with transcribed text, duration, and language. Include `timestamp_granularities: ["word"]` to get word-level timestamps.
**Pricing:** Batch transcription is priced at **1 credit per 2 seconds** of audio processed.
For migrating from the OpenAI SDK, see our [OpenAI Whisper to Cartesia Ink Migration Guide](/use-the-api/migrate-from-open-ai).
## OpenAPI
````yaml /latest.yml POST /stt
openapi: 3.0.1
info:
title: Cartesia API
version: 0.0.1
servers:
- url: https://api.cartesia.ai
description: Production
security: []
paths:
/stt:
post:
tags:
- Stt
summary: Speech-to-Text (Batch)
description: >-
Transcribes audio files into text using Cartesia's Speech-to-Text API.
Upload an audio file and receive a complete transcription response.
Supports arbitrarily long audio files with automatic intelligent
chunking for longer audio.
**Supported audio formats:** flac, m4a, mp3, mp4, mpeg, mpga, oga, ogg,
wav, webm
**Response format:** Returns JSON with transcribed text, duration, and
language. Include `timestamp_granularities: ["word"]` to get word-level
timestamps.
**Pricing:** Batch transcription is priced at **1 credit per 2 seconds**
of audio processed.
For migrating from the OpenAI SDK, see our [OpenAI Whisper to Cartesia
Ink Migration Guide](/use-the-api/migrate-from-open-ai).
operationId: stt_transcribe
parameters:
- $ref: '#/components/parameters/CartesiaVersionHeader'
- name: encoding
in: query
description: >-
The encoding format to process the audio as. Required when uploading
raw PCM data without a container header. If not specified, the audio
file will be decoded automatically from its container (e.g. WAV,
MP3, FLAC). For guidance on choosing an encoding, see [Audio
encodings](/build-with-cartesia/capability-guides/stt-input-encodings).
required: false
schema:
$ref: '#/components/schemas/STTEncoding'
nullable: true
- name: sample_rate
in: query
description: 'The sample rate of the audio in Hz. '
required: false
schema:
type: integer
nullable: true
requestBody:
required: true
content:
multipart/form-data:
schema:
type: object
properties:
file:
type: string
format: binary
model:
description: >-
ID of the model to use for transcription. Use `ink-whisper`
for the latest Cartesia Whisper model.
type: string
language:
description: >-
The language of the input audio in ISO-639-1 format.
Defaults to `en`.
enum:
- en
- zh
- de
- es
- ru
- ko
- fr
- ja
- pt
- tr
- pl
- ca
- nl
- ar
- sv
- it
- id
- hi
- fi
- vi
- he
- uk
- el
- ms
- cs
- ro
- da
- hu
- ta
- 'no'
- th
- ur
- hr
- bg
- lt
- la
- mi
- ml
- cy
- sk
- te
- fa
- lv
- bn
- sr
- az
- sl
- kn
- et
- mk
- br
- eu
- is
- hy
- ne
- mn
- bs
- kk
- sq
- sw
- gl
- mr
- pa
- si
- km
- sn
- yo
- so
- af
- oc
- ka
- be
- tg
- sd
- gu
- am
- yi
- lo
- uz
- fo
- ht
- ps
- tk
- nn
- mt
- sa
- lb
- my
- bo
- tl
- mg
- as
- tt
- haw
- ln
- ha
- ba
- jw
- su
- yue
type: string
nullable: true
timestamp_granularities[]:
description: >-
The timestamp granularities to populate for this
transcription. Currently only `word` level timestamps are
supported.
type: array
items:
$ref: '#/components/schemas/TimestampGranularity'
nullable: true
responses:
'200':
description: ''
content:
application/json:
schema:
$ref: '#/components/schemas/TranscriptionResponse'
security:
- TokenAuth: []
- APIKeyAuth: []
components:
parameters:
CartesiaVersionHeader:
name: Cartesia-Version
in: header
description: API version header.
required: true
schema:
type: string
format: date
example: '2026-03-01'
enum:
- '2026-03-01'
schemas:
STTEncoding:
title: STTEncoding
type: string
enum:
- pcm_s16le
- pcm_s32le
- pcm_f16le
- pcm_f32le
- pcm_mulaw
- pcm_alaw
description: >-
The encoding format for audio data sent to the STT API. Must match the
actual encoding of your audio. For detailed guidance on each format, see
[Audio
encodings](/build-with-cartesia/capability-guides/stt-input-encodings).
TimestampGranularity:
title: TimestampGranularity
type: string
enum:
- word
description: >-
The granularity of timestamps to include in the response.
Currently only `word` level timestamps are supported, providing start
and end times for each word.
TranscriptionResponse:
title: TranscriptionResponse
type: object
properties:
text:
type: string
description: The transcribed text.
language:
type: string
nullable: true
description: The specified language of the input audio.
duration:
type: number
format: double
nullable: true
description: The duration of the input audio in seconds.
words:
type: array
items:
$ref: '#/components/schemas/TranscriptionWord'
nullable: true
description: >-
Word-level timestamps showing the start and end time of each word.
Only included when `[word]` is passed into
`timestamp_granularities[]`.
required:
- text
TranscriptionWord:
title: TranscriptionWord
type: object
properties:
word:
type: string
description: The transcribed word.
start:
type: number
format: double
description: Start time of the word in seconds.
end:
type: number
format: double
description: End time of the word in seconds.
required:
- word
- start
- end
securitySchemes:
TokenAuth:
type: http
scheme: bearer
bearerFormat: JWT
description: A short-lived access token to make API requests from a client.
APIKeyAuth:
type: http
scheme: bearer
bearerFormat: API Key
description: >-
Cartesia API key (`sk_car_...`). Get one at
[play.cartesia.ai/keys](https://play.cartesia.ai/keys).
````