For more about LNBits extension check this tutorial

nostrclient is an always-on extension that can open multiple connections to nostr relays and act as a multiplexer for other clients: You open a single websocket to nostrclient which then sends the data to multiple relays. The responses from these relays are then sent back to the client.

The Test Endpoint functionality heps the user to check that the nostrclient web-socket endpoint works as expected.

The LNbits user can DM itself (or a temp account) from nostrclient and verify that the messages are sent and received correctly.