Methods, systems, and apparatus, including computer programs encoded on computer storage medium, to facilitate interception of messages that include offensive content. In one aspect, a method includes actions of receiving input on a user device that includes message content, determining, on the user device, whether the message content includes offensive content, and in response to determining, on the user device, that the message content includes offensive content, generating an alert message for display on the user device that provides an indication that the message includes offensive content.