Type to search.

#188 by installs

Really Simple CAPTCHA

by Rock Lobster Inc.Version 2.5

Really Simple CAPTCHA is a CAPTCHA module intended to be called from other plugins. It is originally created for my Contact Form 7 plugin.

Active installs
300,000+
#188 of 1,000
Downloads, all time
9.5M
9,481,556
Downloads, 30 days
32K
9.1K in the last 7
Rating
4.2 / 5
131 reviews
Last updated
2 months ago
Aug 23, 2026
Version
2.5
19 releases

Upkeep and compatibility

Last updatedAugust 23, 2026Updated in the last 3 months
Tested up toWordPress 7.1.4Covers WordPress 7.1.4, the current release
Needs WordPress7.1 or newer
Needs PHP8.3 or newer
First publishedMarch 10, 2009
Support, last two months1 of 1 threads resolved (100%)

Reviews

4.2 / 5 from 131 reviews

Reviews by star rating
5 stars92
4 stars15
3 stars1
2 stars4
1 star19

Downloads, last 30 days

Low 362 a dayHigh 3.7K a day

What the author says it does

Really Simple CAPTCHA does not work alone and is intended to work with other plugins. It is originally created for Contact Form 7, however, you can use it with your own plugin.

Note: This product is “really simple” as its name suggests, i.e., it is not strongly secure. If you need perfect security, you should try other solutions.

How does it work?

Really Simple CAPTCHA does not use PHP “Sessions” for storing states, unlike many other PHP CAPTCHA solutions, but stores them as temporary files. This allows you to embed it into WordPress without worrying about conflicts.

When you generate a CAPTCHA, Really Simple CAPTCHA creates two files for it; one is an image file of CAPTCHA, and the other is a text file which stores the correct answer to the CAPTCHA.

The two files have the same (random) prefix in their file names, for example, “a7hk3ux8p.png” and “a7hk3ux8p.txt.” In this case, for example, when the respondent answers “K5GF” as an answer to the “a7hk3ux8p.png” image, then Really Simple CAPTCHA calculates hash of “K5GF” and tests it against the hash stored in the “a7hk3ux8p.txt” file. If the two match, the answer is confirmed as correct.

How to use with your plugin

Note: Below are instructions for plugin developers.

First, create an instance of ReallySimpleCaptcha class:

$captcha_instance = new ReallySimpleCaptcha();

You can change the instance variables as you wish.

The opening of the plugin's own description. The full text, installation notes and changelog are on its WordPress.org page.

Questions the author answers

CAPTCHA does not work; the image does not show up.

Really Simple CAPTCHA needs GD and FreeType library installed on your server. Ask your server administrator if they are installed.

Also, make the temporary file folder writable. The location of the temporary file folder is managed by the instance variable tmp_dir of ReallySimpleCaptcha class. Note that the setting varies depending on the calling plugin.

Latest changelog entry

2.5

  • Bumps up the minimum required WordPress version to 7.1.
  • Bumps up the minimum required PHP version to 8.3.
  • Changes the author name to Rock Lobster Inc. (a Japan-based company that the original author, Takayuki Miyoshi, owns)

Screenshots

From WordPress.org.

Tagged

Plugins that share its tags

#109 by installs

SiteGuard WP Plugin

by jp-secure

Adds WordPress login and admin protections, including CAPTCHA, login lock, login alerts, renamed login URLs, and SiteGuard WAF tuning support.

Installs
600,000+
Rating
4.3 (15)
Updated
4 days ago

#212 by installs

Advanced Google reCAPTCHA

by WebFactory

Captcha protection against spam comments & brute force login attacks using Google reCAPTCHA.

Installs
200,000+
Rating
4.8 (430)
Updated
25 days ago

#237 by installs

Simple CAPTCHA with Cloudflare Turnstile

by Elliot Sowersby / RelyWP

Add Cloudflare Turnstile to WordPress, WooCommerce, Contact Forms & more. The user-friendly, privacy-preserving reCAPTCHA alternative. 100% free!

Installs
200,000+
Rating
4.7 (262)
Updated
1 day ago

#341 by installs

reCaptcha by BestWebSoft

by bestwebsoft

Protect WordPress website forms from spam entries with Google reCAPTCHA.

Installs
100,000+
Rating
3.9 (391)
Updated
6 months ago

#373 by installs

Login Lockdown & Protection

by WebFactory

Protect, lockdown & secure login form by limiting login attempts from the same IP & banning IPs.

Installs
100,000+
Rating
4.3 (61)
Updated
25 days ago

Where this page's numbers come from

Read from the WordPress.org plugin API on , when WordPress 7.1.4 was the current release. WordPress.org rounds active installs into buckets. These are the directory's figures, not my verdict, and I haven't tested this plugin. The author takes donations at their donate page.