UnSave is an extensible (de)serializer for Unreal Engine 4 save files.
In short, this library can be used to read in unencrypted UE4 save files, parse the data/properties included, and (optionally) write that save data back out to a .sav file.
Note that this library is intended for usage in libraries/apps and does not include a user-friendly format. For that, use the excellent gvas-converter.
This library is in an extreme alpha state and probably shouldn't be relied on in it's current state until I've tested and refactored it a bit more.
Huge thanks to @RagingLightning and Ilya/@13xforever for their work on gvas-converter. That tool is amazing and a huge design inspiration (as well as filling in a few gaps in my knowledge) for building this.
Honestly, for most use cases,
gvas-converteris the better choice: UnSave is only intended for scenarios where extensibility and customization are crucial.