As per as my knowledge there is no entrance examination available other then GATE for admission in the M. tech course of IITs.

Except IITs other institutes conduct their own entrance examination for admission in to the M. tech here is the list of these institutes:

BITS Pilani

Jawaharlal Nehru University, Delhi

Guru Gobind Singh Indraprastha University, Delhi

Indraprastha Institute of Information Technology (IIIT), Delhi
International Institute of Information Technology (IIIT), Hyderabad

International Institute of Information Technology (IIIT), Bhubaneswar

International Institute of Information Technology (IIIT), Allahabad

International Institute of Information Technology (IIIT), Kerala

Anna University, Tamil Nadu

Visvesvaraya Technology University, Karnataka
Jamia Milia Islamia University, Delhi
Jawaharlal Nehru Technological University, AP

Punjab University, Chandigarh
Thapar University, Patiala
MH-CET