Various approaches for the packet processing, and the use of templates for generating modification commands for packet processing, are discussed herein. In an example, operations performed by network packet processing circuitry include: obtaining a stream of packets; obtaining a packet modification template that provides at least one command to insert content within the packets and change the packets according to an output format of a network protocol; receiving parameters to modify the packet modification template; and applying the packet modification template to modify the packets. In further examples, application of the packet modification template is performed using multiple processing components arranged in parallel groups of serial pipelines, each of the serial pipelines applying a portion of the packet modification template within at least a first stage and a second stage in each of the serial pipelines.