DigiLocker uses the following tools, APIs & services for providing its document sharing & verification capability.

ownCloud is free, open source software that provides universal access to your files through a web interface. User accounts and document uploading in DigiLocker is based on ownCloud.
Jharkhand Police under the State Government of Jharkhand has a state-of-the-art data centre facility. DigiLocker uses this facility for its development and test environments.
Unique Identification Authority of India (UIDAI) provides a 12 digit unique identity number called Aadhaar to the residents of India. DigiLocker uses authentication and KYC services of Aadhaar to establish account holder's identity.
eMudhra Limited is a Certifying Authority licensed by Controller of Certifying Authorities, under Government of India. The eSign facility in DigiLocker is provided by eMudhra.
National Informatics Centre (NIC) is a premier organization of Government of India which provides IT and IT infrastructure services. DigiLocker is hosted in the National Data Centre provided by NIC.
The Centre for Development of Advanced Computing (C-DAC) is a research and development organization under the Department of Electronics and Information Technology, Govt of India. SMS gateway services of DigiLocker are provided by CDAC.