CurseCollar
Run it from a browser, your phone included.
You buy the collar. The owner HUD is free, and one covers every pet you own. The demo is the whole thing for an hour of wear, not a stripped-down version of it.
Everything the in-world HUD does, in a web page. You do not need to be logged into Second Life.
Movement, chat, teleport, inventory, detaching. Furniture can ask for control through the relay.
Four taps in the collar menu and it is paired. No developer account, no keys, nothing to set up outside SL.
More than one owner if you want. Trustees can play without holding the keys. The safeword cannot be turned off, by anyone.
Every lock, leash and command posted to a channel, if you want the record.
Lock, leash, restrictions and the titler run inside the collar. If this site goes down, the collar does not.