The Sandes app is a secure instant messaging application that has been developed by the National Informatics Centre (NIC), a project funded by the Ministry of Electronics and Information Technology (MEIT), Government of India. 

It is based on the open-source Java platform and is designed to provide an end-to-end secure instant messaging service to Government organizations in India. The app supports end-to-end encryption and allows users to create and manage their own private keys for signing and verification.

This app can be integrated with other Government communications systems to send secure instant messages to the users of those systems. The app also allows the users to send and receive messages to/from the users of other systems who have been added as contacts in the app.