TLDR: It is an implementation of HTTP Bridge API from TON Connect specification.
Bridge is a transport mechanism to deliver messages from the app to the wallet and vice versa.
- Bridge is maintained by the wallet provider. App developers do not have to choose or build a bridge.
- Messages are end-to-end encrypted. Bridge does not see the contents or long-term identifiers of the app or wallet.
- Communication is symmetrical. Bridge does not distinguish between apps and wallets: both are simply clients.
- Bridge keeps separate queues of messages for each recipient’s Client ID.
As of Nov 2024, there isn't an open source implementation of the bridge. There are only two, so called, reference implementations, that cannot be used in production: bridge and bridge2. So many wallets developers either have to implement the bridge spec by themselves, or to use the only popular bridge provider. None of them open-sourced their solutions, which doesn't sound good for The Open Network.
The main idea of this implementation is to encourage wallet developers to host the bridge by themselves.