Apart for different syntax: Plus of NIM: * powerful compiler can produce C, C++, JS, ObjectiveC code * GC can be completely removed to adapt to the program

Apart for different syntax: Plus of NIM: * powerful compiler can produce C, C++, JS, ObjectiveC code * GC can be completely removed to adapt to the program * support parallelism via threading Plus of Crystal: * use of types union permit to mix types in almost every data structure, let you pondering if the langugae is really strong typed * so similar to Ruby that porting a 100-lines library (with no fancy-metaprogramming) to Crystal is often a matter of few hours * use of green threads suits very nicely with HTTP request/response cycle (like GO and Erlang), where using threads/processes is more memory/CPU consuming What Crystal still lacks is parallelism, but core team are working on that. Said that both are modern, fast, elegant languages, with a good standard library and a vibrant community.