Word Cloud is a preset for the Moodle activity database.
Word cloud layout by Jason Davies, http://www.jasondavies.com/word-cloud/, Algorithm due to Jonathan Feinberg, http://static.mrfeinberg.com/bv_ch03.pdf
Users can enter text. A word cloud is generated from all submissions.
Download the release file. Create a "Database" activity in Moodle and then upload the ZIP file in the "Presets" tab under "Import".
The preset is available in German, but there is not so much to translate. The template can easily be adapted.