I made this because every other country tracker I could find was too annoying to use.
You don't need to login or create an account. There isn't yet another password to remember (in fact that's how I built this whole travel agency if you're lucky enough to be one of my clients). You just click the countries you've been to, and it updates the link in the URL bar. Click the share button or copy the link and send it to anyone you want.
This is my list, of the very generous 238 "countries" which I included, which do include a lot of island micro nations with about 37 people. It's always hard to decide what is or isn't a country exactly, just ask Benedict Anderson.