[bbcbasic]

I doubt most of the code I have written has been done before, as most of it relates to the business domain and specifically the parts of the business domain that are currently under focus.

Anything that is generic, e.g. a double entry accounting system, an Actor model, etc. should be in a package management system - a Gem, a Nuget Package, a NPM pacakage etc. rather than copy pasted.

At the micro level for specific line-of-code level problems (usually due to language/platform quirks) we have StackOverflow.