Webapps are small apps developed by players, they synchronize with the server (and sometimes to other servers) at regular intervals, often there is a lag of 10 to 20 minutes. Some apps do not have quite the same IG and out-of-game features (with browser) - please also check the configuration of the API key used (it is convenient to create one key per app).
You can access the apps either in-game or via a browser (log in with your personal name and password).