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The library folder is a large cache containing imported assets and other data from the project after import. It is generally always 100% safe to delete the Library folder. As Unity has become more stable, this has become much less necessary than it once was.
Unity provides this tool in C:\Program Files\Unity\Hub\Editor\2020.2.1f1\Editor\Data\Tools
which allows you to inspect data in the Library folder.
Contains the serialized, imported data keyed by an asset's GUID. 1) binary2text.exe
can be used to dump and view the cached imported data.