CSAB means Central seat allocation board.The Ministry of Human Resource Development, Government of India took a policy decision in 2002 to conduct an All India Engineering Entrance Examination (AIEEE) annually, doing away with many of the large number of entrance examinations that were being conducted till then by various institutes in the country for admission to undergraduate degree programmes in the disciplines of Engineering/Technology and Architecture/Planning. This initiative has been widely accepted and appreciated.A Central Counselling Board (CCB) constituted by the Govt. of India coordinated admissions to UG degree programmes in engineering, technology and architecture in respect of selected institutes till 2012. From 2013 onwards, CCB and AIEEE have been renamed as Central Seat Allocation Board (CSAB) and JEE (Main) respectively. the large number of entrance examinations that were being conducted  by various institutes and universities in the country for admission in BE/ B.Tech/ B.Arch courses, JEE (Main) is conducted by CBSE as a qualifying test.B ut it is fact that many candidates are not able to get admissions in NITs/ Top ranked colleges. Candidates are unknown of this fact that any student who has positive score in JEE main is eligible to get admission in vacant seats of some of the other Top colleges or universities, as most of such colleges have a fixed number of seats for JEE Main rank holders. Counselling For Admission And Selection Board (CSAB) has autonomously endeavoured to make students to know such possibilities and provide details of available seats of vacant seats.The board also conduct counselling process to allot such seat.Yes there is registeration fees for CSAB councelling process.

visit below site to check CSAB counselling process and registration fees:

https://engineering.careers360.com/articles/csab-special-round-for-nits-iits-and-gftis