Systems and methods for screening unauthorized devices are provided. More particularly, a challenge that includes a first set of data can be generated. The challenge can require a browser of a requesting device to perform a browser task with respect to the first set of data to generate a second set of data. The challenge can be provided to the requesting device and a response to the challenge can be received. The response can include the second set of data generated by the browser of the requesting device through performance of the browser task. It can be determined whether the browser of the requesting device is an authorized browser based, at least in part, on the second set of data. Whether or not the requesting device is authorized to access a resource can be based, at least in part, on whether the browser is an authorized browser.