Why does the text stop being selectable?

Greyscale rewrites each page as a picture, so the words are no longer live text.

Does the file get smaller?

Usually it does, because a picture of a page takes less room than a full page of colour objects.

No. Your browser renders the pages and writes the new file.

Turn a colour document into a greyscale copy, for printing and for cheap copies.

Drag & drop a PDF, or choose it from your device. It stays on your machine.

Choose file