Language selection - AssemblyAI

Pass a language_code in the config part to steer transcription toward a specific language. For multilingual or code-switching audio, pass an array of codes instead of a single code.

Accepts a single ISO 639-1 code ("es") or a list of codes (["en", "es"])
Defaults to English (en) when omitted
Ignored when a custom prompt is set — the prompt fully controls the model, so set the language inside the prompt if you also need custom instructions

Python
JavaScript
cURL

import json
import requests

with open("sample.wav", "rb") as f:
    audio = f.read()

response = requests.post(
    "https://sync.assemblyai.com/transcribe",
    headers={
        "Authorization": "<YOUR_API_KEY>",
        "X-AAI-Model": "universal-3-5-pro",
    },
    files={
        "audio": ("sample.wav", audio, "audio/wav"),
        "config": (None, json.dumps({"language_code": "es"}), "application/json"),
    },
    timeout=60,
)
response.raise_for_status()
print(response.json()["text"])

import { readFileSync } from "fs";

const audio = readFileSync("sample.wav");
const form = new FormData();
form.append("audio", new Blob([audio], { type: "audio/wav" }), "sample.wav");
form.append(
  "config",
  new Blob([JSON.stringify({ language_code: "es" })], {
    type: "application/json",
  })
);

const response = await fetch("https://sync.assemblyai.com/transcribe", {
  method: "POST",
  headers: {
    Authorization: "<YOUR_API_KEY>",
    "X-AAI-Model": "universal-3-5-pro",
  },
  body: form,
});

const result = await response.json();
console.log(result.text);

curl -X POST https://sync.assemblyai.com/transcribe \
  -H 'Authorization: <YOUR_API_KEY>' \
  -H 'X-AAI-Model: universal-3-5-pro' \
  -F 'audio=@sample.wav;type=audio/wav' \
  -F 'config={"language_code":"es"};type=application/json'

For multilingual or code-switching audio, pass language_code as an array listing every expected language:

{ "language_code": ["en", "es"] }

Supported languages

Code	Language	Code	Language
`en`	English	`da`	Danish
`es`	Spanish	`fi`	Finnish
`de`	German	`hi`	Hindi
`fr`	French	`vi`	Vietnamese
`it`	Italian	`ar`	Arabic
`pt`	Portuguese	`he`	Hebrew
`tr`	Turkish	`ja`	Japanese
`nl`	Dutch	`ur`	Urdu
`sv`	Swedish	`zh`	Mandarin
`no`	Norwegian

​Supported languages

Supported languages