Tick the 3×3 owner/group/others grid, type an octal like 0755, or edit the symbolic rwxr-xr-x — whichever you change, the other two follow instantly, setuid/setgid/sticky included. Paste the first column of ls -l (file-type character tolerated) and read the plain-language line stating what the mode allows for each audience. Common presets one click away — with a caution on 777.
Privacy ledger
Data acquired
None.
Libraries used
Lit 3 — bundled into the tool file itself.
Data stored
None.
Data transmitted
None.
Use it on your own page
Download the tool as a single self-contained HTML file: readable source with the Lit library included, zero network requests — it works opened straight from your disk, and you can customize everything.