Is there an English version?

Yes, of course!

For yourself, as the admin of a picdrop account, you can switch the language of your account right here in your settings: Userdata & Password

When sending a gallery link to your clients the language of the gallery will automatically switch between English and German depending on the browser of your clients.

If they use a non-German browser, the gallery will be automatically displayed in English. You don't have to do anything. If you want to be on the safe side, you can also set the language in your gallery settings and your clients will always see the galleries in English, no matter what language their computer or browser is set to.