Examples of implementations relate to metadata extraction. For example, a system of privacy preservation comprises a physical processor that executes machine-readable instructions that cause the system to normalize a network traffic payload with a hardware-based normalization engine controlled by a microcode program; parse the normalized network traffic payload, as the network traffic payload passes through a network, by performing a parsing operation of a portion of the normalized network traffic payload with a hardware-based function engine of a plurality of parallel-distributed hardware-based function engines controlled by the microcode program; and provide the hardware-based function engine with a different portion of the normalized network traffic payload responsive to an indication, communicated through a common status interface, that the different portion of the normalized network traffic payload is needed to complete the parsing operation.