LanguageTool API

api.languagetoolplus.com · AI

AI No Auth Free Tier Grammar Writing NLP

Open-source grammar, style, and spell checker for 30+ languages. Detects grammar errors, typos, and style issues. Free tier: 20 requests/minute, 75KB text/request.

Authentication

No authentication requiredFree to use with no key needed.

Sample Requests

POST Check grammar

Check "This are a test." for grammar errors.

https://api.languagetoolplus.com/v2/check

Hover any highlighted part to learn what it does

Headers — extra info sent with the request

Content-Type

application/x-www-form-urlencoded

Request Body — data you're sending

"text=This are a test.&language=en-US"

curl -X POST "https://api.languagetoolplus.com/v2/check" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -H "Content-Type: application/json" \
  -d '"text=This are a test.&language=en-US"'

import requests
headers = {
    "Content-Type": "application/x-www-form-urlencoded"
}
data = "text=This are a test.&language=en-US"
response = requests.post(
    "https://api.languagetoolplus.com/v2/check",
    headers=headers,
    json=data,
)
print(response.json())

const url = 'https://api.languagetoolplus.com/v2/check';

const response = await fetch(url, {
  method: 'POST',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded'
  },
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify("text=This are a test.&language=en-US"),
}); 
const data = await response.json();
console.log(data);

package main

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

func main() {
	targetURL := "https://api.languagetoolplus.com/v2/check"
	jsonData, _ := json.Marshal("text=This are a test.&language=en-US")
	req, _ := http.NewRequest("POST", targetURL, bytes.NewBuffer(jsonData))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	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.languagetoolplus.com/v2/check")

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

req = Net::HTTP::Post.new(uri)
req["Content-Type"] = "application/x-www-form-urlencoded"
req["Content-Type"] = "application/json"
req.body = "\"text=This are a test.&language=en-US\""

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

<?php
$url = "https://api.languagetoolplus.com/v2/check";
$opts = ["http" => [
    "method" => "POST",
    "header" => implode("\r\n", [
        "Content-Type: application/x-www-form-urlencoded",
        "Content-Type: application/json"
    ]),
    "content" => json_encode("text=This are a test.&language=en-US"),
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));

Postman Setup Guide

Get Postman ↗

No API key needed for basic use
POST to /v2/check with form data: text=YOUR_TEXT&language=en-US
Response includes matches array with error positions and suggestions
Languages: en-US, en-GB, de-DE, fr, es, it, nl, pl, pt-BR and more
Self-hostable: docker run -p 8010:8010 silviof/docker-languagetool

Open documentation ↗