Akismet

Akismet is a web-based anti-spam service developed by Automattic and widely used to filter spam from comments, trackbacks, and form submissions on websites, most notably WordPress sites. It functions as a plugin or integrated service and is activated on a site via an API key.

Submitted content is sent to Akismet's servers, where it is analyzed using machine learning, heuristic rules, and crowdsourced data from sites that use Akismet. Each item is given a spam score and classified as spam or legitimate. Site operators can review items flagged as spam or not spam and adjust settings accordingly.

Although originally built for WordPress, Akismet offers APIs and plugins for other platforms. It is available with a free plan for personal sites and paid plans for commercial use, with options to adjust sensitivity and review queues.

Using Akismet involves transmitting data about commenters and visitors to Automattic's servers, including IP addresses, user agents, referrers, and the content of comments. This data handling has privacy implications and is governed by the service's terms and privacy policy, including compliance with data protection laws.

Akismet is widely adopted and effective at reducing spam, though it has faced criticism for false positives and privacy concerns. It remains a standard tool in the WordPress ecosystem.