Inside a CAPTCHA Provider Integration
CAPTCHA providers generally offer both CAPTCHA generation and validation services. To use these
services, the subscribing websites either use the existing libraries and plugins or write their own. A
typical user interaction with a web application that relies on a CAPTCHA provider is summarized below:
1. A user requests a page that requires CAPTCHA validation.
2. The returned page contains an embedded (or ) tag to retrieve the CAPTCHA
image from the CAPTCHA provider.
3. Upon parsing the embedded tags, the browser retrieves a CAPTCHA from the CAPTCHA provider
and displays it to the user.
4. The user fills in the form fields, enters the CAPTCHA solution, and submits the page to the web
application.
5. The web application then submits the CAPTCHA solution to the CAPTCHA provider for verification.
6. The CAPTCHA provider responds to the web application with success or failure message.
7. Based on CAPTCHA provider’s response, the web application allows or denies the request.