XMTP

XMTP is the open protocol and network for secure, interoperable web3 messaging between wallets.

XMTP provides the communication layer for the decentralized web. It enables encrypted, wallet-to-wallet messaging across platforms like Coinbase Wallet and Lens Protocol. By using a permissionless network of nodes, XMTP ensures that messages remain sovereign and portable: if one app disappears, your conversations persist. Developers use the XMTP SDK to integrate reach-outs, alerts, and customer support directly into dApps, reaching over 2 million unique addresses with end-to-end encryption (E2EE) by default.

https://xmtp.org