I am developing a browser extension to make a fill-in-the-blank language test out of any webpage.

I personally used this to improve my German vocabulary. This way one can learn new words from materials they naturally enjoy (vs boring text books).

The extension is available for Chrome: https://chrome.google.com/webstore/detail/vocabboost/obgbcam...? Firefox: https://addons.mozilla.org/en-US/firefox/addon/vocabboost/

There is also a video example here: http://vocabboost.online/.