Is it safe to write custom scripts?

Hey,

I was wondering if it would be safe to write some server calls within custom scripts itself instead of making new apps. Is there any security issues with this approach? Will it be possible for an outside user without any authorization to access my data ?

Thanks in advance

Akarsh

Custom Scripts has nothing to do with security. The security part is handled in the server side calls (which should check credentials before returning any data)