Smile (data interchange format)

Smile is a computer data interchange format based on JSON. It can also be considered a binary serialization of the generic JSON data model, which means tools that operate on JSON may be used with Smile as well, as long as a proper encoder/decoder exists for the tool. The name comes from the first 2 bytes of the 4 byte header, which consist of Smiley ":)" followed by a linefeed: a choice made to make it easier to recognize Smile-encoded data files using textual command-line tools.

Source: Wikipedia — Smile (data interchange format) (CC BY-SA 4.0)