I'm not taking jee main nor the bitsat so can I apply for niit?

yes for NIIT University there will be a seperate exam for Btech entry, candiadte interested can apply through there official website link was here

https://nucleus.niituniversity.in/ug-prog/Login.aspx

or you can purchase the application form from any of NU centers

follow the steps

Step 1: Fill the registration page (by clicking Create Account) with the required details and Register your email id to generate the password.

Step 2: Fill all the fields in the Tabs as described in the application form as per the instructions mentioned.

Step 3: Please do not submit your application until you have entered required details in all the information fields of the application form.

Step 4: After submitting the application form, pay application processing fee online by Credit card/ Debit card/ Net Banking.

Step 5: On successful submission of your online application form, you will get an online application number. Please retain this application ID for future correspondence / reference.

Please note that once you become an applicant for NU program, you can also avail the following services :

1.Check updates / emails and progress of your application.

2.Book your Admission Interaction Process ( AIP ) schedule.

3.Pay Acceptance fee , Enrolment fee and other fee.

4.Book your campus visit.