1. A computer-implemented method comprising: receiving, by a router node of a transformation node cluster comprising a plurality of nodes, a request from a client machine for a content item stored in a repository associated with a server machine that is associated with the transformation node cluster, the transformation node cluster further comprising a plurality of transformation nodes, each of the plurality of transformation nodes being implemented on one or more programmable processors that are separate from other programmable processors upon which other transformation nodes of the plurality of transformation nodes are implemented, each of the plurality of transformation nodes further being configured to execute only one of a plurality of content transformation types; identifying, by the router node, a current content format of the content item and a target content format of the content item, the target content format differing from the current content format; determining, based on the identifying, a chain of transformations, the chain of transformations comprising a first transformation type from the plurality of content transformation types for transforming the content item from the current content format to an intermediate content format; selecting, by the router node, a first node of the plurality of transformation nodes, the router node selecting the first node based on the current content format and the target content format or the intermediate content format matching the only one of the plurality of content transformation types for which the first node is configured; and routing, by the router node, the content item to the first node of the plurality of transformation nodes in the transformation node cluster, the first node of the plurality of transformation nodes being configured to execute the first transformation type of the plurality of content transformation types determined for the content item; storing, in the repository by the router node, a transformed content item resulting from the first node of the plurality of transformation nodes, the transformed content item in the intermediate content format; and transmitting, by the router node and in response to the storing, a reference to the transformed content item, the reference identifying a location in the repository where the transformed content item is stored.