Thanks
I know you are looking for different words, but truly, as a native speaker, I would use 'thanks'. I would say 'thanks' rather than 'thank you' if I was wanting to be informal:
Thanks a lot.
Thanks, man. (Only with someone you know well.)
Thanks, dude. (Only with someone you know well.)
Thanks, bro. (Only with someone you know well.)
You could also say, 'thanks' and add a fist bump or a pat on the back.