7-Zip

7-Zip is a free, open-source file archiver that opens almost everything and compresses tighter than most paid rivals. A plain interface is the only real cost.

Sumatra PDF

Sumatra PDF is a free, no-frills PDF reader that opens files on Windows almost instantly, without Adobe’s bloat. See who it actually fits.

LibreOffice

LibreOffice is a completely free, open source Office & Productivity suite covering six apps, though heavily formatted Word and Excel files don’t always translate perfectly.

Mozilla Firefox

Mozilla Firefox is a free, open-source web browser that runs on its own independent engine, built around strong privacy defaults and deep customization.