Folders
Meet Folders: one free app for 382 kinds of files
Folders is a free, open-source file manager for Android, Windows and Linux that opens PDFs, Office files, 3D models, code, videos and archives itself, with no ads and no account.
Windows
6 guides on this topic.
A Windows file explorer with tabs, and the shortcuts that make it fast
Folders on Windows and Linux: tabs, multiple windows, drag and drop with File Explorer, a see-through window and the keyboard shortcuts you already know. Free and open source.
How to find and remove duplicate files safely
Duplicate photos, videos and downloads waste gigabytes. Find true copies by their contents, not their names, keep the oldest of each and delete the rest, on Android, Windows or Linux.
How to move files between your phone and PC over Wi-Fi, without a cable
Two free ways to send photos, videos and documents between Android and a computer on the same Wi-Fi: a browser link with a QR code, or Nearby share that works with LocalSend.
How to open HEIC photos and convert them to JPG, on Android and Windows
HEIC photos from iPhones won't open everywhere. View them on Android and convert one or a whole batch to JPG, PNG, WebP or AVIF, for free, keeping the originals.
Read and edit PDF, Word and Excel files offline, without an office suite
Open PDF, DOCX, XLSX and PPTX files on Android, Windows or Linux: search, sign PDFs, add notes, edit Word text and spreadsheet cells, present slides, all offline and free.