Documentation
One Captcha
Getting Started

Getting Started

This page describes how to display and customize the One Captcha v3 Developer Beta widget on your web page.

Show One Captcha Widget

Step 1

Import the following One Captcha API JavaScript code into the <head> tag of your HTML page code:

<script src="https://onecaptcha.us.kg/0/api.js"></script>

or

<script src="https://onecaptcha.us.kg/0/api_lite.js"></script>
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We also have a test API (this test API can use some new features, but may not be stable):
<script src="https://onecaptcha.us.kg/0/api_test.js"></script>

Step 2

Add the HTML code that renders One Captcha in the <body> tag of your HTML page file:

<div id="one-captcha" data-callback="Your Callback Function"></div>

Configuration properties

NameDescription
data-callbackThe name of the callback function that is executed when the user submits a successful response. The one captcha token will be passed to your callback.
data-langOptional, this is a custom language, currently supported languages

Verify Captcha Response

After successful verification, One Captcha assigns a hashed ID to the website cookie: a one-time token. It also assigns a non-hashed token to the callback function, which you can retrieve from the cookie after encrypting the non-hashed token to a hashed value. The cookie token is valid for 15 seconds. After this time expires, the token will become invalid and the user must complete the verification process again.

data-callback example: 

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async function CaptchaSuccess(token) {
    // Function to retrieve the value of a cookie by name
    function getTokenCookie(name) {
        const value = `; ${document.cookie}`;
        const parts = value.split(`; ${name}=`);
        if (parts.length === 2) return parts.pop().split(';').shift();
    }

    // Get the OneCaptchaToken cookie
    const cookieToken = getTokenCookie('OneCaptchaToken');

    // Function to hash the token using SHA-512
    async function hashToken(token) {
        const encoder = new TextEncoder();
        const dataBuffer = encoder.encode(token);
        const hashBuffer = await crypto.subtle.digest('SHA-512', dataBuffer);
        const hashArray = Array.from(new Uint8Array(hashBuffer));
        const hashHex = hashArray.map(b => b.toString(16).padStart(2, '0')).join('');
        return hashHex;
    }

    // Compare the hashed token with the cookieToken
    const hashedToken = await hashToken(token); // Hash the passed token
    if (hashedToken === cookieToken) {
        // After successful verification, execute your code here.
    } else {
        // Execute your code here after verification fails.
    }
}
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One CaptchaAttribute