A Web browser of a computing device downloads or otherwise obtains a file. File information identifying the file is obtained and is sent to a remote reputation service. Client information identifying aspects of the computing device can also optionally be sent to the remote reputation service. In response to the file information (and optionally client information), a reputation indication for the file is received from the remote reputation service. A user interface for the Web browser to present at the computing device is determined, based at least in part on the reputation indication, and presented at the computing device.