There are so many website. like yatra.com, ezeego1.co.in, makemytrip.com, cleartrip.com, travelocity.com, travelguru.com, etc etc. you will find different offers on differnet sites. try on these sites and book from where you will get the best fare.
you can also book from direct airline websites e.g goair.in, spicejet.com etc etc.