Signal said on Saturday it had restored its services a day after the application faced technical difficulties as it dealt with a flood of new users after rival messaging app WhatsApp announced a controversial change in privacy terms.
Signal has seen a rise in downloads following a change in WhatsApp's privacy terms, which required WhatsApp users to share their data with both Facebook and Instagram.
Signal users might see errors in some chats as a side effect to the outage, but will be resolved in the next update of the app, the company said in a tweet.
The error does not affect the security of the chat, the company added.
The non-profit Signal Foundation based in Silicon Valley, which currently oversees the app, was launched in February 2018 with Brian Acton, who co-founded WhatsApp before selling it to Facebook, providing initial funding of $50 million.