The Networked Digital Library of Theses and Dissertations (NDLTD) is an international organization dedicated to promoting the adoption, creation, use, dissemination, and preservation of electronic theses and dissertations (ETDs).
https://ndltd.org/thesis-resources/find-etds/

The Shodhganga@INFLIBNET Centre provides a platform for research students to deposit their Ph.D. theses and make it available to the entire scholarly community through open access. The repository has the ability to capture, index, store, disseminate and preserve ETDs submitted by the researchers.
https://shodhganga.inflibnet.ac.in/