Friendly, easy, lightweight, self-hostable CAPTCHA service.
選択できるのは25トピックまでです。 トピックは、先頭が英数字で、英数字とダッシュ('-')を使用した35文字以内のものにしてください。
Skylar Ittner 1c725e7170 Minor text fix 1年前
db_upgrade Add (much) better text questions. 3年前
images Initial commit 3年前
nbproject Initial commit 3年前
.gitignore Initial commit 3年前
.htaccess Rename captcheck.dist.js to captcheck.min.js, update docs 1年前
LICENSE Update license year 1年前
api.php Fix a thing 3年前
captcheck.css Override website theme link borders 2年前
captcheck.js Fix bug where some containers end up with two CAPTCHAs inside 1年前
captcheck.min.js Minor text fix 1年前
composer.json Initial commit 3年前
composer.lock Initial commit 3年前
database.mwb Add (much) better text questions. 3年前
database.sql Add (much) better text questions. 3年前
index.html Rename captcheck.dist.js to captcheck.min.js, update docs 1年前
logo.png Add logo 3年前 Rename captcheck.dist.js to captcheck.min.js, update docs 1年前
required.php Update readme, add SQL code, remove unused function in required.php 3年前
scrapetexts.php Add (much) better text questions. 3年前
settings.template.php Automatically delete old sessions 3年前
test.html Rename captcheck.dist.js to captcheck.min.js, update docs 1年前
test.php Improve output of test.php 1年前


Easy, light, self-hostable CAPTCHA service. Works on modern browsers (and IE9+). Uses a selection of icons from Font-Awesome. Text-only accessibility mode and support for keyboard-only operation.

Thanks to for supplying the data for the text CAPTCHA.

How to use

In your form, put an empty div with the class “captcheck_container”. Add captcheck.js (or captcheck.min.js) into your page.

<!DOCTYPE html>
        <title>Captcheck Sample Form</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <script src="captcheck.js"></script>
        <form action="submit.php">
            <input type="text" name="form_field" placeholder="Some random form field" />
            <div class="captcheck_container">
            <button type="submit">Submit Form</button>

When the form is submitted, your server will receive two extra form fields: captcheck_session_code and captcheck_selected_answer. In your form handling code, send a request to http(s)://captcheck-url/api.php. Pass the variables session_id and answer_id with the values sent with the form, and also pass the variable action with the value verify. You will receive a JSON response with (among other things) "result": true or "result": false. If result is false, the user failed the test, and another variable msg is available with an explanation.

Example URL: http(s)://captcheck-url/api.php?action=verify&session_id=<captcheck_session_code>&answer_id=<captcheck_selected_answer>

Example responses: {"session":"some_session_id","result":true} {"session":"some_session_id","result":false,"msg":"Answer incorrect."}

###Content-Security-Policy and Nonces

Add data-stylenonce="nonce_here" to the .captcheck_container div. If you have multiple CAPTCHAs on one page, only one of them needs the nonce specified.


  1. Run composer install.
  2. Copy settings.template.php to settings.php and plug in your settings.
  3. Install the database.
  4. Customize captcheck.js with the correct api_url.
  5. Follow the How to Use section and the example setup in test.html and test.php.

Execution Flow

JS = captcheck.js, API = api.php, FORM = parent form,
SITE = form processing code, -> = some action taken on the right by the left

JS -> API:      Request session ID, question, and answers (with scrambled random codes)
API -> JS:      Sends info, saves session ID, correct answer, and scrambled answer codes in DB
JS -> API:      Requests answer images by sending scrambled value and session ID
JS -> FORM:     Adds hidden field with value=session ID, displays question and images (or text box)
SITE -> API:    Sends session ID and answer
API -> SITE:    Responds with true/false to indicate if the answer is valid, marks session as expired to prevent CAPTCHA reuse