With Online compiler a programmer can compile/debug his code online and can save and access his code from any where through internet.
There are some circumstances where you don’t have compilers installed on your pc , then you can directly go to the online compilers , paste your code and compile directly without installing compiler on your pc.
Some of the links for Online compilers are:
And there are many more sites that are providing online compilers. You can search in google.
I have not used all these online compilers but, i have used IDE-ONE. And i can say it is the best online IDE or Compiler to compile or run your code. It supports nearly or more than 50 programming languages.