Whatsat is a decentralized and censorship-resistant way to send messages to fellow Lightning Network users. ^[2]

In the second week of November 2019, a Lightning Labs developer named Joost Jager unveiled an experimental protocol allowing users to send messages on the Lightning Network. ^[2]

Whatsat is different from Telegram (software) or Whatsapp because there is no central entity to stop users from using the network. As a decentralized entity, there is no organizational body; there is essentially no one who can grant access to conversations on the network. It is a true peer-to-peer network in which anyone can participate. The Lightning Network is a protocol layered on top of the Bitcoin blockchain. ^[2]

A Bitcoin Core contributor named Sjors Provoost complained that Whatsat wasn't designed to connect to popular existing apps, like Whatsapp or Signal. Jager defended his decision by saying the features are useful on their own:^[2]

Users must agree to a pay for every message they send.

Right now the average user sends about 30 messages a day, which results in a price of about 1 Satoshi per message.

^{[2] [4]}