Methods and systems provide embeddable user interface widgets to third-party applications so that the widgets can be securely embedded in, and securely used from within, the third-party applications. An embeddable widget may be authorized to access a first-party cloud storage system from a third-party application based on the cloud storage system authenticating a request received from the widget. The authentication may be based on an application identifier, an origin identifier, and/or one or more document identifiers received from the third-party application through the embedded widget. The disclosed methods and systems may significantly mitigate security concerns caused by embedding software in third-party sites, such as clickjacking.