Varies with device
A private chat tool: SIGNAL IS OPEN-SOURCE AND A NONPROFIT Open source, non-profit project.
In addition to the normal chat software features: the ability to send voice and make calls directly, with end-to-end encryption.
You can see that the other party is online and is typing.
In fact, this function is similar to the telegraph, you can set the message retention time; for example, accurate to five seconds, one minute, one hour, one day or even a week later, you can automatically "burn" the message, no longer need to manually.
Signal, a free messaging app, is more secure than Telegram and WhatsApp, and offers greater protection of personal privacy. Signal is a free messaging app from Open Whisper Systems, a US-based developer, that supports iPhone, Android, Windows, Mac and Linux platforms. Signal has many advantages in terms of security: peer-to-peer encryption: Signal is long term peer-to-peer encryption, Telegram requires Secret Chats to use peer-to-peer encryption, and WhatsApp also offers peer-to-peer encryption (and uses peer-to-peer encryption powered by Signal). Encryption method: Signal and WhatsApp also use random encryption method, while Telegram uses the developer's own network key for encryption, which means that the government or any organization can decrypt messages as long as it gets the developer's network key. VK behind Telegram and Facebook behind WhatsApp are more famous for collecting user information.