It's totally free and as an SUPost user you might find it useful:
an SUPost Checker Chrome browser extension.

- Notification about recent posts
- Filtering recent posts according to user specified keywords

Installation link
https://chrome.google.com/webstore/detail/supostcom-checker/jiodniiinjkbhnkeagdhbedpolcokdip

You're welcome to install and provide feedback.
I'm not affiliated with the SUPost.com site and developed it independently, therefore not responsible for the use you make of it and the content of the posts.

Happy posting...