Awais

Simple Spam Blocker use honeypot technique which is fast and easy way to prevent spam. This plugin can stop spam comments, spam registration and also can be used to stop bots to try to login into admin panel. This plugin also provide option to stop spammers to get register via Ultimate Memeber Plugin’s registration from. You can also use shortcode [simple-spam-blocker] on any form to stop spammers.

Simple Spam Blocker

Simple Spam Blcoker stop spam comments and also can be used to stop bots to try to login into admin panel.

Otto Kekäläinen

Viljami Kuosmanen

This plugin fights comment and registration spam on your website. This plugin is based on the Open Source WP No-Bot plugin at http://www.compdigitec.com/apps/wpnobot by Compdigitec.
This plugin is authored by <a href="http://seravo.fi/" rel="nofollow ugc">Seravo Oy</a>, which specializes in open source support services and among others is the only company in Finland to provide <a href="http://seravo.fi/wordpress-palvelu" rel="nofollow ugc">WordPress Premium Hosting</a>.
Source available at https://github.com/Seravo/wp-spam-question-filter

WP Spam Question Filter

This plugin fights comment and registration spam on your website.

Simple Spam Blocker vs WP Spam Question Filter