What is software that is completely free?

Software that is completely free comes in three genuinely different kinds — worth telling apart because 'free' hides different deals: open-source software (free forever, source code public, run by communities or companies — LibreOffice, GIMP, VLC, Blender, Linux; the license guarantees it stays free), freeware (free to use but closed — the vendor can change terms, add ads or discontinue it anytime), and free tiers of commercial products (free until you hit limits designed to convert you — generous ones are honest value, stingy ones are extended trials).

The classic warning applies mainly to the middle category: if a closed product is free and you can't see the business model, you might be the product (data, ads, upsell).

Open source is the safest 'completely free' bet — the incentive structure can't quietly flip on you.