GATE https://qualifygate.com/study-material/
https://www.gatexplore.com/study-material/
GRE https://www.ets.org/gre/revised_general/prepare/?WT.ac=gre_prepare_170731
https://www.veritasprep.com/gre/free-gre-resources/
IELTS https://www.ieltsidpindia.com/information/online-ielts-study-material
https://www.britishcouncil.it/en/exam/ielts/courses-resources/free-online-english-preparation-material
TOEFL https://www.ets.org/toefl/ibt/prepare/
Civil Service https://byjus.com/free-ias-prep/
https://www.clearias.com/ias-study-materials/
https://www.civilserviceindia.com/study-material.html