This version of the API shipped with Indigo 2021.2.0 - check the Api Version Chart to see what version of the API is available in which Indigo versions.
<URL> element to [<MenuItem>](../indigo_2021.2_documentation/plugin_guide.md#custom-html-menu-item-dialogs) and [<PluginConfig>](../indigo_2021.2_documentation/plugin_guide.md#custom-html-config-dialogs) elements so that those menus will open a browser URL rather than run a plugin config dialog./messages/ call to the action props dict.[indigo.Dict](../indigo_2021.2_documentation/object_model_reference.md#converting-to-native-python-collections) and [indigo.List](../indigo_2021.2_documentation/object_model_reference.md#converting-to-native-python-collections) instances to the Python equivalents (recursively).[indigo.Device](../indigo_2021.2_documentation/device_class.md#generating-a-dictionary-for-a-device) to a Python [dict](../indigo_2021.2_documentation/device_class.md#generating-a-dictionary-for-a-device)with all properties and states.[self.pluginFolderPath](../indigo_2021.2_documentation/plugin_guide.md#properties))[self.pluginSupportURL](../indigo_2021.2_documentation/plugin_guide.md#properties))[indigo.server.getWebServerURL](../indigo_2021.2_documentation/server_commands.md#get-web-server-url))[indigo.utils](../indigo_2021.2_documentation/object_model_reference.md#utility-classes-and-functions) moduleindigo.utils.JSONDateEncoder)indigo.utils.FileNotFoundError)indigo.Dict to IWS to direct it to stream the contents of a static file back to the requester ([indigo.utils.return_static_file](../indigo_2021.2_documentation/object_model_reference.md#return-static-file))[indigo.utils.validate_email_address](../indigo_2021.2_documentation/object_model_reference.md#validate-email-address))