Documentation

Securimage is a self-hosted PHP CAPTCHA library. These docs cover installation, configuration, and integration. For new projects, skip to the modern alternatives—Securimage still works but barely gets updates.

Getting Started with Securimage

• Quickstart Guide — Add Securimage to a PHP form in minutes: download, display the image, validate server-side.
• Download — Latest release on GitHub. GPL-licensed, free.
• Customizing Securimage — Colors, fonts, dimensions, distortion, line count, character sets.

Reference & Examples

• FAQ — GD errors, session issues, validation failures, hosting-specific problems.
• CAPTCHA Gallery — See what different configurations look like.
• WordPress Plugin — Securimage-WP: protect WordPress comment forms with Securimage.

Modern Alternatives

Securimage dates to 2005. If you're starting fresh, use one of these instead:

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

Comparisons

• Best CAPTCHA Alternatives in 2026 — Side-by-side breakdown of every major option
• reCAPTCHA vs hCaptcha
• Cloudflare Turnstile vs reCAPTCHA
• WordPress CAPTCHA Plugins