A restricted web site has features that are selectively exposed to clients. A screening web site interacts with clients and collects data about the clients using passive and/or active techniques. The screening site generates a token for the client, and includes data in the token identifying the token and describing the client. The token is encoded in a cookie and saved in the client's web browser. The client subsequently provides the token to the restricted site. The restricted site validates the token to ensure that it is legitimate, has not expired, and has not been used before. The restricted site selects one or more features to provide to the client based on the data about the client in the token and/or on other information. If the client does not present a token or the token is invalid, the restricted site does not expose any features to the client.