---
title: "Extracted audio to timed captions; max 12 MB decoded"
method: POST
path: "/transcribe"
---

# Extracted audio to timed captions; max 12 MB decoded

`POST /transcribe`

## Request

- Base URL: `https://api.justcaptions.com/v1`
- URL: `https://api.justcaptions.com/v1/transcribe`
- Auth: HTTP bearer

## Headers

- `Idempotency-Key` string

## Request body

- object
  - `audio_base64` string, required
  - `mime_type` string
  - `language` string
  - `glossary` string[]
  - `format` 'json' | 'srt' | 'vtt'

## Response `200`

Success

- object

## Other responses

- `400`: invalid_request
- `401`: invalid_api_key
- `402`: insufficient_credits (prepaid balance or monthly cap), or payment_required (legacy subscription)
- `409`: idempotency_conflict or request_in_progress
- `422`: duration_mismatch: audio exceeds measured or conservatively reserved duration; request not billed
- `429`: quota_exceeded, free_tier_busy, spend_cap_reached or rate_limited
- `503`: Provider or service unavailable

---

[API](https://skmtc.dev/justcaptions/apis/just-captions-api.md) · [All operations](https://skmtc.dev/justcaptions/apis/just-captions-api/llms.txt) · [OpenAPI document](https://skmtc.dev/justcaptions/apis/just-captions-api/revisions/bbd6b38c1cef?raw)