Jeremy Felt

This plugin attempts to stop spam from the standard WordPress comment field and custom Contact 7 form submissions.
It does not send any data to an external service to determine if submitted content is spam. No cookies or other personal user information are captured or stored.

Self-Sustaining Spam Stopper

Stop spam without relying on an external service.

Pippin Williamson

Modifies the Empty Spam action in WordPress to process the spam deletion in batches, allowing you to delete thousands or even hundreds of thousands of spam comments at once without killing your server.
Have you found a bug or have a suggestion or improvement you’d like to submit? This plugin is available on <a href="https://github.com/pippinsplugins/batch-comment-spam-deletion" rel="nofollow ugc">Github</a> and pull requests are welcome!

Batch Comment Spam Deletion

Modifies the Empty Spam action in WordPress to process the spam deletion in batches instead of all at once.

Self-Sustaining Spam Stopper vs Batch Comment Spam Deletion