Looks like the Great Firewall or something like it is preventing you from completely loading www.skritter.com because it is hosted on Google App Engine, which is periodically blocked. Try instead our mirror:
This might also be caused by an internet filter, such as SafeEyes. If you have such a filter installed, try adding appspot.com to the list of allowed domains.
Kanji In Context by the Inter-University Center Japanese Language Studies, published byJapan Times (Revised 2013). This list contains only the essential vocabulary (red).