Documentation

Securimage is a self-hosted PHP CAPTCHA library. The documentation covers installation, configuration, and integration with modern PHP projects and frameworks. For modern alternatives to Securimage, see the PHP integration guides below.

Getting Started with Securimage

• Quickstart Guide — Add Securimage to any PHP form in minutes. Covers download, displaying the CAPTCHA image, and server-side validation.
• Download — Download the latest Securimage release from GitHub (GPL-licensed, free).
• Customizing Securimage — Change colors, fonts, image dimensions, distortion level, line count, and character sets.

Reference & Examples

• FAQ — Common problems and solutions: GD errors, session issues, validation failures, hosting-specific problems.
• CAPTCHA Gallery — Examples of different Securimage configurations.
• WordPress Plugin — Securimage-WP: protect WordPress comment forms with Securimage.

Modern PHP CAPTCHA Integration

The CAPTCHA landscape has changed significantly since Securimage launched. These guides cover the major modern options:

• Using Cloudflare Turnstile in PHP — Invisible, privacy-respecting, free. The recommended default for new PHP projects in 2026.
• Using Google reCAPTCHA v3 in PHP — Score-based invisible CAPTCHA from Google. High accuracy; note GDPR implications.
• Using hCaptcha in PHP — Privacy-first alternative to reCAPTCHA. Free tier shows image puzzles; Enterprise is invisible.

Comparing Your Options

• Best CAPTCHA Alternatives in 2026 — Full comparison of every major option
• reCAPTCHA vs hCaptcha
• Cloudflare Turnstile vs reCAPTCHA
• WordPress CAPTCHA Plugins