PrismJS! I tried out the other two, Prettify and SyntaxHighlighter, and I just preferred the look of PrismJS. Prism had a lot more themes to choose from and pretty good language support. I've included some examples below of how some code in 3 different languages might appear. I'm assuming most of what I post will be in Python or C/C++, but occasionally I mess around with Go, Erlang and Scala, so those might also make an appearance on the site. Unfortunately there is no Scala or Erlang support, so I might just have to add it . . .

C++

    #include <iostream>

    int main() {
        std::cout << "Hello, world!" << std::endl;

        return (0);
    }
    
    

Python


    def hello_world():
        print("Hello, world!")


    if __name__ == '__main__':
        hello_world()

    

Scala (PrismJS doesnt actually support scala, so this is with Java highlighting)


    def factorial(n: Int): Int = {
        if (n == 0)
            return 1
        else
            return n * factorial(n - 1)
    }