Audio to Text

Transcribe Audio

post

Transcribes audio to text in the original language using openai/whisper-1. Supports MP3, MP4, MPEG, M4A, WAV, WEBM formats (max 25MB). Output formats: json, text, srt, vtt, verbose_json.

Authorizations

bearerAuth

AuthorizationstringRequired

FastRouter API Key. Get yours at https://fastrouter.ai

Format: Authorization: Bearer YOUR_API_KEY

Body

multipart/form-data

filestring · binaryRequired

Audio file to transcribe. Supported formats: mp3, mp4, mpeg, mpga, m4a, wav, webm. Max size: 25MB

modelstring · enumRequired

Model to use for transcription. Must be 'whisper-1' or 'openai/whisper-1'

Example: whisper-1Possible values:

languagestringOptional

Optional: ISO-639-1 language code of the audio (e.g., 'en', 'es', 'fr', 'de'). Improves accuracy and latency.

Example: en

promptstringOptional

Optional: Text prompt to guide the transcription style or continue a previous segment. Can include punctuation, casing, or specific vocabulary.

response_formatstring · enumOptional

Output format:

• json: Basic JSON with text field
• text: Plain text only
• srt: SubRip subtitle format
• vtt: WebVTT subtitle format
• verbose_json: JSON with metadata and timestamps

Default: jsonPossible values:

temperaturenumber · max: 1Optional

Sampling temperature (0-1). Lower values make output more focused and deterministic. Higher values increase randomness.

Default: 0

Responses

200

Transcription successful

application/jsontext/plain

Responseone of

or

400

Bad Request - Invalid file format or parameters

401

Invalid Credentials - Your API key is invalid, disabled, or your OAuth session has expired. Check your credentials.

application/json

413

Payload Too Large - File exceeds 25MB limit

429

Rate Limited - You have exceeded your request limits (TPM/RPM). Slow down or increase your limits.

application/json

500

Internal Server Error

post

/audio/transcriptions

HTTPcURLJavaScriptPython

POST /api/v1/audio/transcriptions HTTP/1.1
Host: api.fastrouter.ai
Authorization: Bearer YOUR_SECRET_TOKEN
Content-Type: multipart/form-data
Accept: */*
Content-Length: 91

{
  "model": "whisper-1",
  "file": "(binary: audio.mp3)",
  "language": "en",
  "response_format": "json"
}

Basic Transcription (JSON)Verbose JSON with MetadataSRT Subtitle FormatPlain Text OutputWith Style Prompt

{
  "text": "Hello, this is a sample transcription of the audio file."
}

Translate Audio to English

post

Translates audio to English text using openai/whisper-1, regardless of source language. Supports MP3, MP4, MPEG, M4A, WAV, WEBM formats (max 25MB). Output formats: json, text, srt, vtt, verbose_json.

Authorizations

bearerAuth

AuthorizationstringRequired

FastRouter API Key. Get yours at https://fastrouter.ai

Format: Authorization: Bearer YOUR_API_KEY

Body

multipart/form-data

filestring · binaryRequired

Audio file to translate to English. Supported formats: mp3, mp4, mpeg, mpga, m4a, wav, webm. Max size: 25MB

modelstring · enumRequired

Model to use for translation. Must be 'whisper-1' or 'openai/whisper-1'

Example: whisper-1Possible values:

promptstringOptional

Optional: English text prompt to guide the translation style. Can help with proper nouns, acronyms, or domain-specific vocabulary.

response_formatstring · enumOptional

Output format:

• json: Basic JSON with translated English text
• text: Plain English text only
• srt: SubRip subtitle format (English)
• vtt: WebVTT subtitle format (English)
• verbose_json: JSON with metadata and timestamps

Default: jsonPossible values:

temperaturenumber · max: 1Optional

Sampling temperature (0-1). Lower values (e.g., 0.1) make output more focused and deterministic. Use 0 for most consistent translations.

Default: 0

Responses

200

Translation successful - output is in English

application/jsontext/plain

Responseone of

or

400

Bad Request - Invalid file format or parameters

401

Invalid Credentials - Your API key is invalid, disabled, or your OAuth session has expired. Check your credentials.

application/json

413

Payload Too Large - File exceeds 25MB limit

429

Rate Limited - You have exceeded your request limits (TPM/RPM). Slow down or increase your limits.

application/json

500

Internal Server Error

post

/audio/translations

HTTPcURLJavaScriptPython

POST /api/v1/audio/translations HTTP/1.1
Host: api.fastrouter.ai
Authorization: Bearer YOUR_SECRET_TOKEN
Content-Type: multipart/form-data
Accept: */*
Content-Length: 84

{
  "model": "whisper-1",
  "file": "(binary: speech_spanish.mp3)",
  "response_format": "json"
}

Basic Translation (Spanish to English)Verbose JSON with MetadataEnglish SRT SubtitlesPlain English TextWith Vocabulary Prompt

{
  "text": "Hello, this is a sample translation to English."
}