Free AI Detector API and Widget

How to add it

1. Create a free account and confirm your email, or sign in.
2. Create a widget key and list the websites where the widget will appear. Do it in the builder above, or on the Widgets page of your account.
3. Choose your options in the builder, then copy the script tag. Use the iframe code instead if your site blocks scripts.
4. Paste it into your page where the detector should appear, then save and publish.

Notes for common platforms. We tested plain HTML. The rest should work in the way described, but we haven't tested them yet.

• Plain HTML (tested): paste the code inside the <body> of your page.
• WordPress (should work, not tested yet): add a Custom HTML block and paste the code. Some security plugins strip scripts, so use the iframe code if the widget doesn't show.
• Google Sites (should work, not tested yet): Insert, then Embed, then Embed code. Paste the iframe code.
• Wix and Squarespace (should work, not tested yet): add an HTML embed or Code block and paste either code.
• Blogger (should work, not tested yet): switch the post to HTML view and paste the code.

Widget keys. The key in the code isn't secret. When the widget loads, our server checks which website shows it and only loads it on the websites listed on that key. On any other site it shows a short notice instead. Add example.com and it also works on www.example.com. Add *.example.com for every subdomain, and localhost for testing. Widgets added without a key keep working until 11 November 2026.

The widget works best with a wide spot on your page, such as the main content column. You can put several widgets on one page. Each gets its own box and its own options.

REST API

Send text to one address and get a JSON result. Call it from your server with your free API key. The API is for websites, and the page that uses it shows a link to WrittenCheck.

POST https://writtencheck.com/api/v1/detect
Authorization: Bearer YOUR_API_KEY
Content-Type: application/json

{"text": "...", "language": "auto", "sentences": true}

API keys

1. Create a free account with Google or your email, and confirm the email.
2. Open API keys, press New key and enter the web page where you will use the API. Copy the key right away. We only show it once.
3. Show a visible link to WrittenCheck on that page, near the tool: AI detection by <a href="https://writtencheck.com">WrittenCheck</a>. A nofollow link is fine.
4. Send it with every call, as Authorization: Bearer YOUR_API_KEY or X-API-Key: YOUR_API_KEY.

Your account page shows every call, day by day, with errors and results, so you can see how your integration behaves. Keep keys on your server. Don't put them in a web page or an app where people can read them. If one leaks, revoke it and make a new one.

The credit link. We check the page when you create the key and then automatically: every few hours while the key is new, and every few days after that. You don't need to press anything once the link is up. A new key works for 7 days while you add the link, and we email a reminder 2 days before the end. If the page still has no visible link after the 7 days, the key is revoked automatically and your account and that website can't get a new key for 7 days. If a link that was there disappears, we email you and the key keeps working for 7 more days. Hidden links, links with no text and pages that show the link only to our checker don't count. Every call needs a key. A call without one gets 401 api_key_required. Don't want to write code or add a link? The widget has the credit built in.

Request fields

The body must be JSON, sent with Content-Type: application/json, and no bigger than 100 KB.

Response

{
  "ok": true,
  "version": "v1",
  "score": 87,
  "range": {"low": 74, "high": 96},
  "confidence": "moderate",
  "verdict": "likely_ai",
  "language": "en",
  "words": 212,
  "sentences": [{"text": "...", "score": 91}],
  "note": "Scores are estimates, not proof of authorship."
}

This shows the shape of a reply. The examples further down show real replies.

Errors

Every error has the same shape: {"ok": false, "error": "code", "message": "plain words"}.

Each reply also carries X-RateLimit-Limit, X-RateLimit-Remaining and X-RateLimit-Reset (a Unix time). With a key, the limit shown is your account's daily limit. The API answers the CORS preflight and sets no cookies.

Examples

Replace YOUR_API_KEY with your own key. The outputs below are real replies from the live API on 4 October 2026, copied unedited, from before keys were added. A call with a key today returns the same fields plus engine. We ran the JavaScript example in a browser. For curl, Python and PHP we sent the same request from a browser too, because the reply is the same whichever tool sends it. The human text is the opening of Pride and Prejudice by Jane Austen (1813). The AI text was written by an AI model for this page. Both are short, so the confidence is low.

curl

curl -s https://writtencheck.com/api/v1/detect \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text": "It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife. However little known the feelings or views of such a man may be on his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding families, that he is considered the rightful property of some one or other of their daughters.", "sentences": false}'

Output

{"ok":true,"version":"v1","score":0,"range":{"low":0,"high":20},"confidence":"low","verdict":"likely_human","language":"en","words":70,"note":"Scores are estimates, not proof of authorship."}

JavaScript (fetch)

const res = await fetch("https://writtencheck.com/api/v1/detect", {
  method: "POST",
  headers: { "Authorization": "Bearer YOUR_API_KEY", "Content-Type": "application/json" },
  body: JSON.stringify({
    text: "Remote work has reshaped how teams collaborate, communicate and measure success. By embracing flexible schedules and digital tools, organizations can tap into a wider talent pool while helping employees achieve a healthier work-life balance. However, this shift also requires clear expectations, intentional communication and a strong culture of trust to keep everyone aligned and engaged.",
    sentences: false
  })
});
const data = await res.json();
console.log(res.status, JSON.stringify(data));

Output

200 {"ok":true,"version":"v1","score":100,"range":{"low":80,"high":100},"confidence":"low","verdict":"likely_ai","language":"en","words":55,"note":"Scores are estimates, not proof of authorship."}

Python (requests)

import requests

text = ("It is a truth universally acknowledged, that a single man in possession of a good fortune, "
        "must be in want of a wife. However little known the feelings or views of such a man may be on "
        "his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding "
        "families, that he is considered the rightful property of some one or other of their daughters.")
r = requests.post("https://writtencheck.com/api/v1/detect", json={"text": text},
                  headers={"Authorization": "Bearer YOUR_API_KEY"})
print(r.status_code)
print(r.text)

Output

200
{"ok":true,"version":"v1","score":0,"range":{"low":0,"high":20},"confidence":"low","verdict":"likely_human","language":"en","words":70,"sentences":[{"text":"It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife.","score":6},{"text":"However little known the feelings or views of such a man may be on his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding families, that he is considered the rightful property of some one or other of their daughters.","score":2}],"note":"Scores are estimates, not proof of authorship."}

PHP (curl)

<?php
$text = "Remote work has reshaped how teams collaborate, communicate and measure success. By embracing flexible schedules and digital tools, organizations can tap into a wider talent pool while helping employees achieve a healthier work-life balance. However, this shift also requires clear expectations, intentional communication and a strong culture of trust to keep everyone aligned and engaged.";
$ch = curl_init("https://writtencheck.com/api/v1/detect");
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_HTTPHEADER => ["Authorization: Bearer YOUR_API_KEY", "Content-Type: application/json"],
    CURLOPT_POSTFIELDS => json_encode(["text" => $text, "sentences" => false]),
    CURLOPT_RETURNTRANSFER => true,
]);
$body = curl_exec($ch);
echo curl_getinfo($ch, CURLINFO_HTTP_CODE), "\n", $body, "\n";

Output

200
{"ok":true,"version":"v1","score":100,"range":{"low":80,"high":100},"confidence":"low","verdict":"likely_ai","language":"en","words":55,"note":"Scores are estimates, not proof of authorship."}

A text that's too short

curl -s https://writtencheck.com/api/v1/detect \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text": "This sentence is much too short to check."}'

Output

{"ok":false,"error":"insufficient_text","message":"Send at least 40 words. Short texts don't give the detector enough to go on.","minimum_words":40,"words":8}

Limits and fair use

The widget and the API are free. API calls are limited per account. The widget has per-IP limits. These are the numbers in our code today.

With the widget, each visitor to your site counts against their own IP address. With an API key, calls count against your account wherever they come from. If you need more, email writtenchecksupport@gmail.com and tell us about your project. Please don't try to get round the limits.

Privacy

• Text sent through the widget or the API is checked in memory and then thrown away. We don't store it, log it or train on it.
• For each check we keep a short record without the text: the time, country, language, word count, score, verdict and which detector answered. Calls with a key are linked to your account so you can see your usage. We don't record which site a widget check came from.
• The widget sets no cookies, uses no browser storage and loads nothing from other companies.
• Your page only gets results if you turn on events, and then it gets the score and verdict, never the text.
• Results are estimates. Don't use a score as the only reason to decide anything about a person. Our privacy policy and terms cover the widget and the API.

Common questions

Changelog

• v1.5, 14 October 2026: credit checks run automatically. Keys still without the link after 7 days are revoked, with a 7-day wait before a new key.
• v1.4, 14 October 2026: every API call needs a key, and each key belongs to one web page that shows a link to WrittenCheck. New keys get 7 days to add the link.
• v1.3, 13 October 2026: the widget code now needs a free widget key, which only works on the websites you list. Widgets added without a key keep working until 11 November 2026, then show a notice.
• v1.2, 12 October 2026: free API keys with per-account limits and a usage page. Calls with a key go to our neural detector first and return an engine field. Calls without a key work until 11 November 2026.
• v1.1, 4 October 2026: the widget now uses the same two-panel design as the detector on writtencheck.com, with the result shown next to the text.
• v1, launched 4 October 2026.