I found a blog post about it and it shares 30+ expression to use.
Here is the my favorites:
- Don't mention it!
- It's my pleasure!
- Glad to help!
- No need at all!
- That's what good [friends|colleagues] do!
- Any time!
- I know you’d do the same for me.
- You deserve it.
Also there are some funny ones:
- You'll get my bill in the morning. :)
- I'll count on your vote in the next election! :)