Under 500 lines, this probably barely qualifies as a library, but it still allows packing structs and containers to/from binary blobs with as little effort as possible.

It has virtually no dependencies, requires no pre-processing (like ProtoBufs do) and it should be easy to understand and extend. It knows how to handle basic types and std containers and then uses a couple of C++ features to coerce the compiler into auto-generating all needed methods for custom types.

All you need to do is to specify which struct/class members must be serialized and then call store() on an instance to produce a blob. To restore an instance - feed the blob into parse() and that's it.

This was originally written to implement an IPC protocol for a pair of cooperating processes, but it can be readily reused for quickly storing data on disk and other things.