Chargie promises to prolong the quality of your phone’s battery life.
Never heard of the tool, but by the sound of it, it extends your battery life by letting you not charge to 100% (e.g. only charge to 80%).
That’s real. Doing that will prolong the life of your battery.
Should you pay $25 for a tool that will do that? Well, if you’re on Android 12 (edit: and your device manufacturer has implemented it), there may be an option in the battery settings to limit charging to 85% which gives you most of the benefit.
If you’re not on Android 12 but have a rooted phone, you can get a free app that does the same thing.
If protecting the battery is important to you, you don’t have a rooted phone (and don’t want to root it), and don’t have Android 12, then as far as I can tell from reviews, Chargie does do what it says.
Doing that will prolong the life of your battery.
Why? What is the difference between charging just upto 80% and 100%?
Because the battery is less stressed when it is in percentages near 50% than if it is in percentages near 100% or 0% AFAIK.