Abstract: Accelerated throttling for web servers and services is provided. Request data may be collected for requests submitted to servers at a datacenter and a request metric and a window determined based on the collected information. The request metric may define a limit for a number of requests from a source to be accepted within the window. Incoming requests for the servers at the datacenter may be monitored and, in some cases, sources for the requests identified. If a number of requests from a source exceed the determined request metric within the window, further requests from the same source may be denied until the window expires. The incoming requests for the servers at the datacenter may be monitored by counting a subset of the incoming requests associated with the identified source, for example.