We are still working as quickly as possible to bring additional capacity online to handle peak traffic levels, it said in another tweet early on Saturday.
While users have been able to open the app and send messages, nothing is being delivered at the moment. For now, the app has also added a banner on top of chats that mentions - “Signal is experiencing technical difficulties. We are working hard to restore service as quickly as possible.”
Compared to the other two, Telegram and WhatsApp, Signal collects no data from its users and has also promised that it is never going to share user data or show in-app ads.
Signal had recently said the Indian market has "completely exceeded all expectations" and that the growth in the past few days has driven the company to add capacity to meet the burgeoning demand.
Signal is a non-profit organisation and operates on donations from individuals, corporate donors and grants, similar to the Wikipedia model.