Adblock Plus is browser extension which will block Ads and popups while browsing the internet.

uBlock Origin is a free and open source, cross-platform browser extension for content-filtering, including ad-blocking.

Disconnect lets you visualize and block the invisible sites that track your search and browsing history.

Easy Youtube Video Downloader is a cross-browser, cross-platform and free web-browser add-on to perform conversion on external servers.

AdBlock is one of the most popular ad blockers.

PDF.js. A general-purpose, web standards-based platform for parsing and rendering PDFs.

uMatrix is a point-and-click matrix-based firewall, with many privacy-enhancing tools.