Formcheck is a static Website that allows to check whether the forms of a Lexeme in Wikidata conforms to the paradigm provided by a function in Wikifunctions.
It let's the user choose a language, a part of speech, the grammatical features of the output form, and a function on Wikifunctions. It then checks whether the function evaluating on the lemma indeed results in the output form.
You can select an arbitrary Z-id for the function, not just one from the given list. You can also choose arbitrary Q-ids in all the above fields, although the system tries to offer you sensible choices.
This video demonstrates the early version: https://commons.wikimedia.org/wiki/File:Checking_forms.webm
This is deployed on Github pages: https://vrandezo.github.io/formcheck