Most of the files in a data directory of a MongoDB server are made by the WiredTiger storage engine. If you want to look at the content inside them you can use the tool wt from the WiredTiger library: https://github.com/wiredtiger/wiredtiger/ http://source.wiredtiger.com/10.0.0/command_line.html Inspection of the WiredTiger files is not an essential MongoDB DBA skill  its [&]

https://www.percona.com/blog/2021/05/18/wiredtiger-file-forensics-part-1-building-wt/