Aspects of the disclosure relate to real-time classification of content in a data transmission. A computing platform may detect, in real-time and via a computing device, a plurality of data transmissions between applications over a communications network. Then, the computing platform may retrieve, for a particular data transmission of the plurality of data transmissions, a content of the particular data transmission. The computing platform may then analyze, via the computing device, the content. Subsequently, the computing platform may determine, in real-time via the computing device and based on the analyzing, a security classification for the content. Then, the computing platform may cause, in real-time via the computing device, the content to be marked with the determined security classification.