Decrypting synthetic transactions with beacon packets is provided. A probe receives, from a client device, a start beacon packet that identifies a test of a service provided by one or more servers. The probe establishes, responsive to receipt of the start beacon packet, a log for the test. The probe stores, in the log established responsive to the start beacon packet, data packets transmitted between the client device and the one or more servers subsequent to the start beacon packet and encrypted with a key using a security protocol. The probe receives, from the client device, key information used to decrypt the data packets of the test encrypted with the key using the security protocol. The probe provides at least one of the data packets for evaluation or decryption using the key information to determine a performance of the service.