Arvados

http://pygments.org/docs/cmdline/

for example:

hello.c:

#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv) { printf("hello\n"); }

$ pygmentize -O full,style=colorful -f html -o hello.c.html hello.c

There's probably plenty more, like https://github.com/github/linguist.

Client side opens up a lot of possibilities:

• https://highlightjs.org/usage/
• https://craig.is/making/rainbows
• http://alexgorbatchev.com/SyntaxHighlighter/manual/installation.html
• https://github.com/google/code-prettify