We recommend to protect your form agains bots using a captcha.
A "Captcha" is a challenge-response test to ensure, that the form is filled out by a human and not by a machine (bot). The program includes multiple captcha styles. e.g.
There is an input field below the captcha image, in which the user should enter the 5 chars. If the user did not enter the right characters, then an error message will be shown and a new ramdom captcha code will be generated. The script will generate a random captcha code and captcha image each time the form will be displayed.
- No cookies required
- No database required
- No fonts required
(The images and script code is included in the single php file generated by the program.)
- Captcha code will be saved on the server (using php SESSIONS)
The user cannot submit the form multiple times, e.g. using the browsers back button (A new random captcha code will be created if the user tries to submit the page again.) A random captcha code will be generated each time a form page will be displayed You can use one of the included captcha styles or let the php script randomize the captcha styles.
- All characters are uppercase in the captcha image, but it will also accept lower
case characters in the response.
- The captcha/script uses the GD php extension, which should be present on most php installations.
Important: A captcha will not give you 100% security. It cannot protect your form against a highly sophisticated attack, but it will block most spam bots and makes life a bit easier.