The subject disclosure is directed towards a technology by which a computing device user may share context-related information (e.g., including current activity) with other recipient machines. A requestor may request to peek at a user's context, and if the requestor is valid (pre-approved by the user), a response based on context-related information is sent, which may be via a cloud service. The response may be filtered and/or adjusted based upon the identity of the requestor and other information associated with that identity, e.g., filtering criteria set by the user. Also described is notifying the user of the peek request, and logging information corresponding to the request and response. A broadcast message may also be sent by the device to share context without waiting for a peek request.