A simple geofencing (polygon-creation) tool built on Leaflet. Check out the demo.
Check bower.json for specific dependency versions
Add dist/leaflet.geofencer.min.js into your HTML file.
<script type="text/javascript" src="proxy.php?url=https%3A%2F%2Fgithub.com%2Fleaflet.geofencer.min.js"></script>
Remember to include dependencies. They can be found in bower_components (exclude unneeded files -- Bower installation included more than necessary).