A network-based production service is configured to process client requests for the production service via a network, capture production request data defining the requests and store the production request data in a data store. A test system comprising one or more controllers creates test jobs according to a test plan for testing the production service. The test plan creates a test profile for using specified production request data to simulate a load on the production service. Each job created by the test plan specifies a portion of production request data. A job queue receives and queues test jobs from one or more controllers configured to add test jobs to the job queue according to the test plan. Workers access jobs from the job queue and the production request data from the data store as specified in each job and replay the production request data to the production service.