If this reddit change did not occurred, I probably never had tried Lemmy (even if I’m in OSS world for 20+ years now). First thought is that I don’t think communities going black or mods leaving reddit will do anything to reddit, it’s so big and alternative are somehow a niche for geek that they will not loose most of their user base. For mods they’ll find out some way … On the other hand, I don’t care, I’m happy here on the fediverse, I participated more discussion here in 1 month than in years on reddit. I had bad experience on my first posts on reddit (probably not interesting enough for some and then downvoted a lot), and I think that I just always thought if my post will be appreciated or not and so and finally just didn’t post. I don’t have this feeling here.

What about the license? is it open source?

Same as yours +

• https://wandbox.org : an alternative to God bolt, when just needing to quickly test something (i.e. not needing the disassembly and multiple options of godbolt, just see if it compiles, or behave like expected on several compilers - I use that very often when writing code review comments to be sure not to advise rubbish…)
• https://regex101.com/ : not specifically for c++ but useful as well

Some great blogs too:

• https://www.fluentcpp.com/ : unfortunately not maintained anymore but many great articles mainly on readability
• https://www.cppstories.com/p/start-here/
• https://www.modernescpp.com/index.php
• https://arne-mertz.de/ : simplify c++

One must see YouTube video: https://youtu.be/2olsGf6JIkU

Perhaps some others I’ll look tomorrow on my work computer.