A system and method for traffic classification using snippets and on-the-fly traffic classifiers can build traffic classifiers that leverage interpretable feature sets without the need to inspect payloads—ensuring functionality across clear-text and encrypted flows. In one embodiment, the system identifies n-grams (“snippets”) in a network flow's sequence-of-message-lengths that are strongly indicative of a given class of traffic and predicts a network flow's class by assessing the presence of snippets relevant to different classes.