Dynamic coordination and control of network connected devices within a distributed processing platform is disclosed for large-scale network site testing, or for other distributed projects. For network site testing, the distributed processing system utilizes a plurality of client devices which are running a client agent program associated with the distributed computing platform and which are running potentially distinct project modules for the testing of network sites or other projects. The participating client devices can be selected based upon their attributes and can receive test workloads from the distributed processing server systems. In addition, the client devices can send and receive poll communications that may be used during processing of the project to control, manage and coordinate the project activities of the distributed devices. If desired, a separate poll server system can be dedicated to handling the poll communication and coordination and control operations with the participating distributed devices during test operations, thereby allowing other server tasks to be handled by other distributed processing server systems. Once the tests are complete, the results can be communicated from the client devices to the server systems and can be reported, as desired. Additionally, the distributed processing system can identify the attributes, including device capabilities, of distributed devices connected together through a wide variety of communication systems and networks and utilize those attributes to organize, manage and distribute project workloads to the distributed devices.