wats - License
Current releases of wats are made under the GNU GPL version 3. Future versions, however, will be distributed under the GNU AGPL version 3 which has more specific clauses for web-based software.
Providing Source
If you're using an unmodified version of wats, you don't need to worry about distributing source code; the footer of every page of wats links back to our sourceforge project page.
If you've made modifications, please also modify the footer to link to the modified source. Also, please submit a pach! There are probably more users of wats out there who would benifit from your changes, and the easiest way for you to distribute them is to have them included in the official version!