I want to make career in software engineering, so I'm preparing for IIT in FIITJEE. What would be the best option if I fail to crack IIT?

Just focus on your studies. Keep an eye on your target (JEE Advance). Elsewise you don't have to worry, there are a number of reputed colleges in India other than IITs like BITS Pilani, Birla Institute of Technology-Mesra, BMS College of Engineering-Bangalore, College of Engineering-Guindy, College

Hello Niki, There are many private colleges for CSE: 1) Jadavpur University 2) BITS Pilani 3) VIT Vellore 4) Thapar University 5) RVCE Bangalore 6) MSRIT Bangalore 7) LNMIT Jaipur 8) MANIPAL Institute of Technology 9) JIIT Noida 10) KIIT

Don't ever think about failure, always keep a positive attitude and motivate yourself with what you aim to do and what will get you there. Software engineering can be done from any institute, all the institutions in India teach basically the same thing.