We relly on openssl pretty heavily already, so why not use its base64 support instead of the one I originaly wrote myself.
I originaly refused to use it, because it seems hard/complicated to use and I already had a header only implementation in a personal project which I just had to drop in.

However I recently found out there seems to be a way easier approach to use it now:
https://stackoverflow.com/a/60580965/7992576

Might be worth checking out.