Hey @Jinu, the best tool I've come across is selenium. Few advantages are mentioned below:
- It is free and open source
 
- It has a large user base and helping communities
 
- It has cross Browser compatibility (Firefox, chrome, Internet Explorer, Safari etc.)
 
- It has great platform compatibility (Windows, Mac OS, Linux etc.)
 
- It supports multiple programming languages (Java, C#, Ruby, Python, Pearl etc.)
 
- It has fresh and regular repository developments
 
- It supports distributed testing