Prosopo Procaptcha is a drop-replacement for reCAPTCHA and hCaptcha that protects user privacy and collects zero data.
Sign up for free and get your sitekey today. You need a sitekey to use this library.
Prosopo captcha can be easily implemented in your application via a script tag or a React component.
First, you must include the Procaptcha JavaScript resource somewhere in your HTML page. The <script> must be loaded
via HTTPS and can be placed anywhere on the page. Inside the <head> tag or immediately after the .procaptcha container
are both fine.
<script type="module" src="https://js.prosopo.io/js/procaptcha.bundle.js" async defer></script>Now, you can either render the Procaptcha widget implicitly or explicitly.
Add an empty DOM container where the Procaptcha widget will be inserted automatically. The container is
typically a <div> (but can be any element) and must have class procaptcha and a data-sitekey attribute set to your
public
site key.
<body>
<div class="procaptcha" data-sitekey="your_site_key"></div>
</body>Typically, you'll want to include the empty .procaptcha container inside an HTML form. When a captcha is successfully
solved, a hidden JSON payload will automatically be added to your form that you can then POST to your server for
verification. You can retrieve it server side with POST parameter procaptcha-response.
Here's a full example where Procaptcha is being used to protect a signup form from automated abuse. When the form is
submitted, the procaptcha-response token will be included with the email and password POST data after the captcha
is solved.
<html>
<head>
<title>Procaptcha Demo</title>
<script type="module" src="https://js.prosopo.io/js/procaptcha.bundle.js" async defer></script>
</head>
<body>
<form action="" method="POST">
<input type="text" name="email" placeholder="Email" />
<input type="password" name="password" placeholder="Password" />
<div class="procaptcha" data-sitekey="your_site_key"></div>
<br />
<input type="submit" value="Submit" />
</form>
</body>
</html>If you prefer to render the widget yourself, you can use the Procaptcha.render() method. The Procaptcha.render()
must be called after the procaptcha.bundle.js script has loaded.
The script is loaded in the head of the document and given the id procaptcha-script. A container is created with the
id procaptcha-container where the widget will be rendered.
<html>
<head>
<script
type="module"
id="procaptcha-script"
src="https://js.prosopo.io/js/procaptcha.bundle.js"
async
defer
></script>
</head>
<body>
<div id="procaptcha-container"></div>
</body>
</html>An onload event is added to the script tag to call the render function when the script has loaded.
// A function that will call the render Procaptcha function when the procaptcha script has loaded
document.getElementById('procaptcha-script').addEventListener('load', function () {
// Define a callback function to be called when the CAPTCHA is verified
function onCaptchaVerified(output) {
console.log('Captcha verified, output: ' + JSON.stringify(output))
}
// Get the Element using elementId
const captchaContainer = document.getElementById('procaptcha-container')
// Render the CAPTCHA explicitly on a container with id "procaptcha-container"
window.procaptcha.render(captchaContainer, {
siteKey: 'YOUR_SITE_KEY',
theme: 'dark',
callback: onCaptchaVerified,
})
})The Procaptcha.render() function takes an options object as its second argument. The options object can contain the
following fields:
| Key | Type | Description | Required |
|---|---|---|---|
| siteKey | string | The site key of your application / website. This is required. | ✓ |
| callback | function | The function that will be called when the CAPTCHA is verified. | ✗ |
| theme | string | The theme of the CAPTCHA widget. The default is light. The other option is dark. |
✗ |
| captchaType | string | The type of CAPTCHA to render. The default is frictionless. Other options are image, pow. |
✗ |
| chalexpired-callback | string | The name of the window function that will be called when the CAPTCHA challenge expires. | ✗ |
| error-callback | string | The name of the window function that will be called when an error occurs. | ✗ |
| close-callback | string | The name of the window function that will be called when the CAPTCHA is closed. | ✗ |
| open-callback | string | The name of the window function that will be called when the CAPTCHA is opened. | ✗ |
| expired-callback | string | The name of the window function that will be called when the CAPTCHA solution expires. | ✗ |
| challenge-valid-length | number | The amount of time, in milliseconds, a successful CAPTCHA challenge is valid for. Defaults to 2 minutes. | ✗ |
The same options can be passed to the implicit rendering method by adding them as data attributes to the .procaptcha.
For example, to set the theme to dark, you would add data-theme="dark" to the .procaptcha container.
<div class="procaptcha" data-sitekey="your_site_key" data-theme="dark"></div>You can choose to implement any of the following types of captcha when rendering the Procaptcha component:
| Type | Description |
|---|---|
frictionless |
The default CAPTCHA type is frictionless. This type of CAPTCHA is invisible to the user, only requiring them to complete an invisible Proof of Work challenge (pow). Suspected bots are served image captcha challenges (image). |
pow |
The pow CAPTCHA type requires the user to solve a cryptographic puzzle. This puzzle simply requires a small amount of computational work to solve, and slows down bots significantly, making it difficult for them to scrape in high volumes. |
image |
The image CAPTCHA type requires the user to solve a simple image CAPTCHA. This is CAPTCHA type most people are familiar with, created by Google reCAPTCHA. |
You must import Procaptcha, define a config with ProcaptchaConfigSchema, optionally define callbacks, and render via the Procaptcha component. A minimal example would be as follows:
import { Procaptcha } from '@prosopo/procaptcha-react'
import { ProcaptchaConfigSchema } from '@prosopo/types'
const MyApp = () => {
const config = ProcaptchaConfigSchema.parse({
account: {
address: 'YOUR_SITEKEY',
},
// Other config options, see demos/client-example for more details
})
return <Procaptcha config={config} />
}
export default MyAppFurther example usage can be seen in demos/client-example
By adding the client side code, you were able to render a Procaptcha widget that identified if users were real people or automated bots. When the captcha succeeded, the Procaptcha script inserted unique data into your form data, which is then sent to your server for verification. The are currently two options for verifying the user's response server side:
To verify that the token is indeed real and valid, you must now verify it at the API endpoint:
https://api.prosopo.io/siteverify
The endpoint expects a POST request with the procaptcha-response token. You must also pass your secret key, which you can obtain by logging in to our customer portal.
A simple test will look like this, where the contents in data is the procaptcha-response token, after being
parsed:
// pseudocode
// get the contents of the procaptcha-response token
data = req.body['procaptcha-response']
// send a POST application/json request to the API endpoint
response = POST('https://api.prosopo.io/siteverify', {
token: data.token,
secret: 'your_secret_key',
})Or, as a CURL command:
curl --location 'https://api.prosopo.io/siteverify' \
--header 'Content-Type: application/json' \
--data '{"secret":"0x1234123412341234123412341234","token":"PROCAPTCHA-RESPONSE"}''Note that the endpoint expects the application/json Content-Type. You can see exactly what is sent using
curl -vvin the example above.
So far, we only have a TypeScript implementation of the Procaptcha verification package. However, we are working on delivering additional language support in the future.
To verify a user's response using TypeScript, simpy import the verify function from @prosopo/server and pass it
the procaptcha-response POST data. Types can be imported from @prosopo/types.
import {ProsopoServer} from '@prosopo/server'
import {ApiParams} from '@prosopo/types'
...
// parse the body received from the frontend
const payload = JSON.parse(event.body)
// parse the procaptcha response token
const procaptchaResponse = payload[ApiParams.procaptchaResponse]
// initialise the `ProsopoServer` class
const prosopoServer = new ProsopoServer(config, pair)
// check if the captcha response is verified
if (await prosopoServer.isVerified(procaptchaResponse)) {
// perform CAPTCHA protected action
}There is an example TypeScript server side implementation in demos/client-example-server.
Custom timeouts can be specified for the length of time in which a user has to solve the CAPTCHA challenge. The defaults are as follows:
const defaultCaptchaTimeouts = {
image: {
// The timeframe in which a user must complete an image captcha (1 minute)
challengeTimeout: 60000,
// The timeframe in which an image captcha solution remains valid on the page before timing out (2 minutes)
solutionTimeout: 60000 * 2,
// The timeframe in which an image captcha solution must be verified server side (3 minutes)
verifiedTimeout: 60000 * 3,
// The time in milliseconds that a cached, verified, image captcha solution is valid for (15 minutes)
cachedTimeout: 60000 * 15,
},
pow: {
// The timeframe in which a pow captcha solution remains valid on the page before timing out (1 minute)
challengeTimeout: 60000,
// The timeframe in which a pow captcha must be completed and verified (2 minutes)
solutionTimeout: 60000 * 2,
// The time in milliseconds that a Provider cached, verified, pow captcha solution is valid for (3 minutes)
cachedTimeout: 60000 * 3,
},
}To specify timeouts using API verification, pass the above object in a field called timeouts, implementing one or more of the timeouts.
// send a POST application/json request to the API endpoint
response = POST('https://api.prosopo.io/siteverify', {
...
timeouts: defaultCaptchaTimeouts, // add timeouts object here
})To specify timeouts using the verification package, pass the above object in the timeouts field of the ProsopoServer config, implementing one or more of the timeouts.
config = { timeouts: defaultCaptchaTimeouts, ...config }
const prosopoServer = new ProsopoServer(config, pair)Procaptcha's default frictionless feature dynamically detects if the user is a bot or a human. If the user is likely
to be a bot, the user will be presented with a Proof-of-Work CAPTCHA challenge. If the user is likely to be a human, the
user will not be presented with an image CAPTCHA challenge.
Serve different types of CAPTCHA by setting the captchaType to frictionless, pow, image.
<div class="procaptcha" data-sitekey="your_site_key" data-captcha-type="frictionless"></div>document.getElementById('procaptcha-script').addEventListener('load', function () {
function onCaptchaVerified(output) {
console.log('Captcha verified, output: ' + JSON.stringify(output))
}
// Get the Element using elementId
const captchaContainer = document.getElementById('procaptcha-container')
window.procaptcha.render(captchaContainer, {
siteKey: 'YOUR_SITE_KEY',
theme: 'dark',
callback: onCaptchaVerified,
captchaType: 'image', // `pow` or `frictionless`
})
})You can view an end-to-end example of how to implement Procaptcha in a React application in our client-example and client-example-server packages. Details of how to run the examples are in the documentation at the previous links.
You can view an example of the bundle being used in a simple HTML page in the client-bundle-example. This example is frontend only.