A server interacts with a bot detection service to provide bot detection as a requesting client interacts with the server. In an asynchronous mode, the server injects into a page a data collection script configured to record interactions at the requesting client, to collect sensor data about the interactions, and to send the collected sensor data to the server. After the client receives the page, the sensor data is collected and forwarded to the server through a series of posts. The server forwards the posts to the detection service. During this data collection, the server also may receive a request from the client for a protected endpoint. When this occurs, and in a synchronous mode, the server issues a query to the detection service to obtain a threat score based in part on the collected sensor data that has been received and forwarded by the server. Based on the threat score returned, the server then determines whether the request for the endpoint should be forwarded onward for handling.