Developers Guide
Display and Verification
Website visitor requests page that includes Lemin Captcha.
The requested page, containing JavaScript for Lemin Captcha, is sent.
Website visitor's browser requests Lemin Captcha from our server.
Requested Lemin Captcha images are sent to the website visitor.
Lemin Captcha data is posted to your website, which contains the website visitor’s encrypted answer.
Your website validates the website visitor’s answer by making a request to the Lemin server.
The Lemin server responds with the verification result.
Your website can allow the website visitor, or show an error according to the received verification result.
Registration and Login
Simply log in to Lemin as an existing user, or sign up as a new user.
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Generating JavaScript Code for Captcha
Just select and copy the JavaScript code from your Lemin Captcha lists. Don’t see any code in your list? Simply click the ‘+ Add New’ button to create a new Captcha.
Displaying Lemin Captcha
Add an empty TAG where you want to display your Lemin Captcha:
<div id="lemin-captcha"></div>
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Following this step. Paste JavaScript code below the tag. (Don’t place the code inside the tag.)
The code can be placed just above your ‘Submit’ or ‘Login’ button.
We have also made it possible for you to add your Captchas programmatically:
const captchaContainer = document.getElementById('lemin-captcha');
const leminScript = document.createElement('script');
leminScript.setAttribute('src', `...`);
captchaContainer?.parentNode?.appendChild(leminScript);
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Obtaining the Site Visitor’s Result
We pass POST data to your server.
To do this, your server just needs to send 'lemin_challengekey' and 'lemin_answer' in POST data to the Lemin server.
Private Key and Verification
A private key is used for verifying site ownership. You can find your unique private key in the ‘Account’ section of your Lemin Dashboard.
Verifying a Captcha Answer
To verify a Lemin Captcha answer from a website visitor, simply pass the following parameters to our server, via the verification URL (Via POST method).
Verification URL for Lemin Puzzle Captcha
https:/lemin-saas-api-staging.herokuapp.com/captcha/v1/cropped/validate
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After Verification
The Lemin server will return one of the following values. The first line will always contain the words ‘true’ or ‘false’. The second line contains error code.
Hello Lemin.
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