Title: Really Simple CAPTCHA Author: Rock Lobster Inc. Published: March 10, 2009 Last modified: February 1, 2025 --- Search plugins ![](https://ps.w.org/really-simple-captcha/assets/banner-772x250.png?rev=880406) ![](https://ps.w.org/really-simple-captcha/assets/icon-256x256.png?rev=1047241) # Really Simple CAPTCHA By [Rock Lobster Inc.](https://profiles.wordpress.org/rocklobsterinc/) [Download](https://downloads.wordpress.org/plugin/really-simple-captcha.2.4.zip) * [Details](https://en-ca.wordpress.org/plugins/really-simple-captcha/#description) * [Reviews](https://en-ca.wordpress.org/plugins/really-simple-captcha/#reviews) * [Installation](https://en-ca.wordpress.org/plugins/really-simple-captcha/#installation) * [Development](https://en-ca.wordpress.org/plugins/really-simple-captcha/#developers) [Support](https://wordpress.org/support/plugin/really-simple-captcha/) ## Description Really Simple CAPTCHA does not work alone and is intended to work with other plugins. It is originally created for [Contact Form 7](https://contactform7.com/), 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. ``` // Change the background color of CAPTCHA image to black $captcha_instance->bg = array( 0, 0, 0 ); ``` See really-simple-captcha.php if you are interested in other variables. Generate a random word for CAPTCHA. ``` $word = $captcha_instance->generate_random_word(); ``` Generate an image file and a corresponding text file in the temporary directory. ``` $prefix = wp_rand(); $captcha_instance->generate_image( $prefix, $word ); ``` Then, show the image and get an answer from respondent. Check the correctness of the answer. ``` $correct = $captcha_instance->check( $prefix, $the_answer_from_respondent ); ``` If the $correct is true, go ahead. Otherwise, block the respondent — as it would appear not to be human. And last, remove the temporary image and text files, as they are no longer in use. ``` $captcha_instance->remove( $prefix ); ``` That’s all. If you wish to see a live sample of this, you can try [Contact Form 7](https://contactform7.com/captcha/). ## Screenshots * [[ * screenshot-1.png ## Installation In most cases you can install automatically from WordPress. However, if you install this manually, follow these steps: 1. Upload the entire `really-simple-captcha` folder to the `/wp-content/plugins/` directory. 2. Activate the plugin through the ‘Plugins’ menu in WordPress. FYI: There is no “control panel” for this plugin. ## FAQ ### 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. For example, Contact Form 7 uses `wp-contents/uploads/wpcf7_captcha` as the temporary folder basically, but it can use different folder depending on your settings. If you have any further questions, please submit them [to the support forum](https://en-ca.wordpress.org/support/plugin/really-simple-captcha). ## Reviews ![](https://secure.gravatar.com/avatar/e627f34d1ed130ebc94bb0ca9314b4bafc8ab7d021047522bd4b25d643f858a8? s=60&d=retro&r=g) ### 󠀁[Prima, funktioniert auch auf meiner WP 6.9 einwandfrei](https://wordpress.org/support/topic/prima-funktioniert-auch-auf-meiner-wp-6-9-einwandfrei/)󠁿 [afudo1tlg](https://profiles.wordpress.org/afudo1tlg/) January 13, 2026 Super simple! Einfach in Contact Form 7 Version 6.1.4 einzubinden. Danke. Meine WordPress Installation: Version 6.9.PHP Version 8.4.15 ![](https://secure.gravatar.com/avatar/102d46bc8cc18bdb8bb252de26388aafa9186150f904007befeaf514af4c1f52? s=60&d=retro&r=g) ### 󠀁[Bad](https://wordpress.org/support/topic/bad-353/)󠁿 [Diego Soto](https://profiles.wordpress.org/diego-soto/) September 15, 2025 1 reply I’m sorry to have to give this a bad rating. The amount of spam with Contact Form 7 was enormous. I had to remove it. ![](https://secure.gravatar.com/avatar/bed0303e15fbaf6ccf27290abc29160870a170e0eb5265e01a0c8c649c8574c7? s=60&d=retro&r=g) ### 󠀁[Works great with Gravity Forms in 2024!](https://wordpress.org/support/topic/works-great-with-gravity-forms-in-2024/)󠁿 [Maxcom](https://profiles.wordpress.org/maxcom/) August 19, 2024 Nothing but positives. We added this to our Gravity Form in order to obtain the dynamic math captcha. One can create a simple math captcha in GF but not dynamically changing for each form load insofar as I can determine. And GF google captcha Ver 3 is a pain with the need for google api keys. So we added this plugin and it was very easy – add the captcha field to the form, select “math” in the settings for the field and done! We find that Gravity Forms Zero Spam plugin was helping to deter spam entries but it with this captcha is 100% so far for spam prevention. Thank you Takayuki Miyoshi! ![](https://secure.gravatar.com/avatar/c910362dbfbd49f8ec8c185f618f4db62e2842297530d6f8bc8cf903d26da6c9? s=60&d=retro&r=g) ### 󠀁[Good Simple Banner](https://wordpress.org/support/topic/good-simple-banner/)󠁿 [nicolasvsedeco](https://profiles.wordpress.org/nicolasvsedeco/) October 25, 2023 Helo, very simple banner for cookies but there is a little bug. The banner Cookies are shown in Widgets page. ![](https://secure.gravatar.com/avatar/a9f956dcdf45addfd12c942879c61a6fa5c9c113e674409a0b825e47c0ae94ac? s=60&d=retro&r=g) ### 󠀁[Bad and not work to stabilite](https://wordpress.org/support/topic/bad-and-not-work-to-stabilite/)󠁿 [gurcantet](https://profiles.wordpress.org/gurcantet/) April 11, 2023 spam is continue to come… ![](https://secure.gravatar.com/avatar/ec51b32c53259c5d1abbbf367b2ca7b3f19775f179f869d413ca0f103cdd6515? s=60&d=retro&r=g) ### 󠀁[test](https://wordpress.org/support/topic/test-132/)󠁿 [rahzan](https://profiles.wordpress.org/rahzan/) September 16, 2022 we [ Read all 129 reviews ](https://wordpress.org/support/plugin/really-simple-captcha/reviews/) ## Contributors & Developers “Really Simple CAPTCHA” is open source software. The following people have contributed to this plugin. Contributors * [ Rock Lobster Inc. ](https://profiles.wordpress.org/rocklobsterinc/) * [ Takayuki Miyoshi ](https://profiles.wordpress.org/takayukister/) “Really Simple CAPTCHA” has been translated into 41 locales. Thank you to [the translators](https://translate.wordpress.org/projects/wp-plugins/really-simple-captcha/contributors) for their contributions. [Translate “Really Simple CAPTCHA” into your language.](https://translate.wordpress.org/projects/wp-plugins/really-simple-captcha) ### Interested in development? [Browse the code](https://plugins.trac.wordpress.org/browser/really-simple-captcha/), check out the [SVN repository](https://plugins.svn.wordpress.org/really-simple-captcha/), or subscribe to the [development log](https://plugins.trac.wordpress.org/log/really-simple-captcha/) by [RSS](https://plugins.trac.wordpress.org/log/really-simple-captcha/?limit=100&mode=stop_on_copy&format=rss). ## Changelog #### 2.4 * Bumps up the minimum required WordPress version to 6.6. * Introduces the ReallySimpleCaptcha_Filesystem trait. * Uses SHA-256 as the hash algorithm. * Uses `wp_rand()` instead of `mt_rand()`. ## Meta * Version **2.4** * Last updated: **1 year ago** * Active installations: **300,000+** * WordPress Version: ** 6.6 or higher ** * Tested up to: **6.7.5** * PHP Version: ** 7.4 or higher ** * Language: * [Albanian](https://sq.wordpress.org/plugins/really-simple-captcha/), [Basque](https://eu.wordpress.org/plugins/really-simple-captcha/), [Catalan](https://ca.wordpress.org/plugins/really-simple-captcha/), [Chinese (China)](https://cn.wordpress.org/plugins/really-simple-captcha/), [Chinese (Taiwan)](https://tw.wordpress.org/plugins/really-simple-captcha/), [Croatian](https://hr.wordpress.org/plugins/really-simple-captcha/), [Czech](https://cs.wordpress.org/plugins/really-simple-captcha/), [Danish](https://da.wordpress.org/plugins/really-simple-captcha/), [Dutch](https://nl.wordpress.org/plugins/really-simple-captcha/), [Dutch (Belgium)](https://nl-be.wordpress.org/plugins/really-simple-captcha/), [English (Australia)](https://en-au.wordpress.org/plugins/really-simple-captcha/), [English (Canada)](https://en-ca.wordpress.org/plugins/really-simple-captcha/), [English (New Zealand)](https://en-nz.wordpress.org/plugins/really-simple-captcha/), [English (South Africa)](https://en-za.wordpress.org/plugins/really-simple-captcha/), [English (UK)](https://en-gb.wordpress.org/plugins/really-simple-captcha/), [English (US)](https://wordpress.org/plugins/really-simple-captcha/), [French (Canada)](https://fr-ca.wordpress.org/plugins/really-simple-captcha/), [French (France)](https://fr.wordpress.org/plugins/really-simple-captcha/), [Galician](https://gl.wordpress.org/plugins/really-simple-captcha/), [German](https://de.wordpress.org/plugins/really-simple-captcha/), [Hungarian](https://hu.wordpress.org/plugins/really-simple-captcha/), [Italian](https://it.wordpress.org/plugins/really-simple-captcha/), [Japanese](https://ja.wordpress.org/plugins/really-simple-captcha/), [Lithuanian](https://lt.wordpress.org/plugins/really-simple-captcha/), [Marathi](https://mr.wordpress.org/plugins/really-simple-captcha/), [Persian](https://fa.wordpress.org/plugins/really-simple-captcha/), [Portuguese (Brazil)](https://br.wordpress.org/plugins/really-simple-captcha/), [Romanian](https://ro.wordpress.org/plugins/really-simple-captcha/), [Russian](https://ru.wordpress.org/plugins/really-simple-captcha/), [Slovak](https://sk.wordpress.org/plugins/really-simple-captcha/), [Spanish (Argentina)](https://es-ar.wordpress.org/plugins/really-simple-captcha/), [Spanish (Chile)](https://cl.wordpress.org/plugins/really-simple-captcha/), [Spanish (Colombia)](https://es-co.wordpress.org/plugins/really-simple-captcha/), [Spanish (Ecuador)](https://es-ec.wordpress.org/plugins/really-simple-captcha/), [Spanish (Mexico)](https://es-mx.wordpress.org/plugins/really-simple-captcha/), [Spanish (Spain)](https://es.wordpress.org/plugins/really-simple-captcha/), [Spanish (Venezuela)](https://ve.wordpress.org/plugins/really-simple-captcha/), [Swahili](https://sw.wordpress.org/plugins/really-simple-captcha/), [Swedish](https://sv.wordpress.org/plugins/really-simple-captcha/), [Tibetan](https://bo.wordpress.org/plugins/really-simple-captcha/), [Turkish](https://tr.wordpress.org/plugins/really-simple-captcha/), and [Ukrainian](https://uk.wordpress.org/plugins/really-simple-captcha/). * [Translate into your language](https://translate.wordpress.org/projects/wp-plugins/really-simple-captcha) * Tag: * [captcha](https://en-ca.wordpress.org/plugins/tags/captcha/) * [Advanced View](https://en-ca.wordpress.org/plugins/really-simple-captcha/advanced/) ## Ratings 4.2 out of 5 stars. * [ 90 5-star reviews ](https://wordpress.org/support/plugin/really-simple-captcha/reviews/?filter=5) * [ 15 4-star reviews ](https://wordpress.org/support/plugin/really-simple-captcha/reviews/?filter=4) * [ 1 3-star review ](https://wordpress.org/support/plugin/really-simple-captcha/reviews/?filter=3) * [ 4 2-star reviews ](https://wordpress.org/support/plugin/really-simple-captcha/reviews/?filter=2) * [ 19 1-star reviews ](https://wordpress.org/support/plugin/really-simple-captcha/reviews/?filter=1) [Your review](https://wordpress.org/support/plugin/really-simple-captcha/reviews/#new-post) [See all reviews](https://wordpress.org/support/plugin/really-simple-captcha/reviews/) ## Contributors * [ Rock Lobster Inc. ](https://profiles.wordpress.org/rocklobsterinc/) * [ Takayuki Miyoshi ](https://profiles.wordpress.org/takayukister/) ## Support Got something to say? Need help? [View support forum](https://wordpress.org/support/plugin/really-simple-captcha/) ## Donate Would you like to support the advancement of this plugin? [ Donate to this plugin ](https://contactform7.com/donate/)