DeepL API

api-free.deepl.com · AI

AI API Key Free Tier Translation NLP Language

High-quality neural machine translation — widely regarded as the best for European languages. Free tier: 500,000 characters/month. Supports 33 languages, documents, and glossaries.

Authentication

API Key Free API key at deepl.com/pro-api (requires account). Pass as Authorization: DeepL-Auth-Key YOUR_KEY header.

Sample Requests

POST Translate text

Translate English to German.

https://api-free.deepl.com/v2/translate

Hover any highlighted part to learn what it does

Headers — extra info sent with the request

Content-Type	application/json
Authorization	DeepL-Auth-Key YOUR_KEY

Request Body — data you're sending

{
  "text": [
    "Hello, how are you?"
  ],
  "target_lang": "DE"
}

curl -X POST "https://api-free.deepl.com/v2/translate" \
  -H "Content-Type: application/json" \
  -H "Authorization: DeepL-Auth-Key YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text":["Hello, how are you?"],"target_lang":"DE"}'

import requests
headers = {
    "Content-Type": "application/json",
    "Authorization": "DeepL-Auth-Key YOUR_KEY"
}
data = {
    "text": [
        "Hello, how are you?"
    ],
    "target_lang": "DE"
}
response = requests.post(
    "https://api-free.deepl.com/v2/translate",
    headers=headers,
    json=data,
)
print(response.json())

const url = 'https://api-free.deepl.com/v2/translate';

const response = await fetch(url, {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'Authorization': 'DeepL-Auth-Key YOUR_KEY'
  },
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
  "text": [
    "Hello, how are you?"
  ],
  "target_lang": "DE"
}),
}); 
const data = await response.json();
console.log(data);

package main

import (
	"fmt"
	"io"
	"net/http"
	"bytes"
	"encoding/json"
)

func main() {
	targetURL := "https://api-free.deepl.com/v2/translate"
	jsonData, _ := json.Marshal({"text":["Hello, how are you?"],"target_lang":"DE"})
	req, _ := http.NewRequest("POST", targetURL, bytes.NewBuffer(jsonData))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "DeepL-Auth-Key YOUR_KEY")
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{}
	resp, _ := client.Do(req)
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	fmt.Println(string(body))
}

require "net/http"
require "json"

uri = URI("https://api-free.deepl.com/v2/translate")

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"

req = Net::HTTP::Post.new(uri)
req["Content-Type"] = "application/json"
req["Authorization"] = "DeepL-Auth-Key YOUR_KEY"
req["Content-Type"] = "application/json"
req.body = "{\"text\":[\"Hello, how are you?\"],\"target_lang\":\"DE\"}"

res = http.request(req)
puts JSON.parse(res.body)

<?php
$url = "https://api-free.deepl.com/v2/translate";
$opts = ["http" => [
    "method" => "POST",
    "header" => implode("\r\n", [
        "Content-Type: application/json",
        "Authorization: DeepL-Auth-Key YOUR_KEY",
        "Content-Type: application/json"
    ]),
    "content" => json_encode({"text":["Hello, how are you?"],"target_lang":"DE"}),
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));

Postman Setup Guide

Get Postman ↗

Sign up at deepl.com/pro-api for a free key (500K chars/month)
Set Authorization: DeepL-Auth-Key YOUR_KEY
Free tier uses api-free.deepl.com; paid uses api.deepl.com
Text is an array — you can translate multiple strings in one call
Languages: EN, DE, FR, ES, IT, NL, PL, PT, RU, JA, ZH and more

Open documentation ↗