If you keep Chrome up-to-date without changing any settings, any PDF you download may open within the web browser by default.

Notepad saves a file in .txt format. By using Print to PDF and Save As options, you can save it as PDF and HTML in Windows 11/10.

Gimp is normally used to create or manipulate images files, but can also work with PDFs if you understand how it works and what it's limits are.

PDF Candy is the rare free PDF editor that offers a lot of the features you’d typically have to pay for. We’re talking scanning, multiple file-conversion options, and OCR functionality.

This free online tool is great for converting and making simple changes to PDF files, but look elsewhere for serious annotation abilities.