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.
Every API request is measured for CPU usage and requests return 429 once a daily limit is reached. This is just an informal safeguard against excessive API usage and internal logical errors (say, in case an API gets into an infinite loop of spawning requests through batching).
Limits are on a user-by-user basis, so clients are not penalized for having many users.
The current limit is about a billion megacycles (Mcycles). Downloading all Items and Vocabs (including all related sentences, top mnemonics, and decomps) for a relatively large account in one large batch takes in the neighborhood of a few million Mcycles.