Hello Vansh, 

             Yes you can get into some of the top NITs like NIT Rourkela with 30,000 rank(according to previous year cutoffs), if you don't have any branch preferences.

You can go thorugh the following link for top NITs cutoff ranks:

https://engineering.careers360.com/articles/nits-cutoff-for-top-btech-branches

Best Wishes!

Hello Student, 

With 30000 general rank you can not get top NITs but yes you can get other NITs like:
NIT Manipur,  NIT Mizoram, NIT Agartala,  NIT Srinagar etc.

In that case you can search other institutes on basis of your Jee Score here:
https://engineering.careers360.com/jee-main-college-predictor
Hope this will help.
Feel free to ask any doubts.