Your location, in the file
A photo from a phone usually records exactly where it was taken, to a few metres, along with the camera, its serial number, and the second you pressed the shutter. None of that is visible when you look at the picture.
Your photo knows
where you live.
See exactly what a picture is carrying about you, then take it out without touching the image itself. Your photo never leaves your device.
What this removes
The picture is untouched
Removing metadata rewrites the container around your image, not the image itself. The pixels come out byte for byte identical, so nothing is re-compressed and no quality is lost.
Smaller is a separate tool
Stripping never re-encodes, so it cannot make the file smaller. If that is what you are after, the compressor does re-encode it, in your browser, and re-checks the result the same way this page does.
Checked, not claimed
After stripping, blakstrip re-reads the finished file from scratch and lists anything still in it. The clean verdict comes from reading the output, not from trusting the code that wrote it.