Connecto

The mod allows offline accounts to join a server that verifies players against Mojang session servers, bypassing that check for listed usernames. Whitelisted names are set in the Connecto config, and the mod is disabled by default so unwanted connections are blocked until an owner turns it on. Once configured, a server accepts both online accounts and whitelisted offline accounts.

Server owners manage the mod in-game through Connecto commands, which require operator status: a status command shows the current state, and a reload command applies changes to the whitelist, including adding and removing names. Editing the config file, which the mod generates on first start, takes effect after the server restarts. Skins can also be fetched for offline players, so an offline account can show an official Mojang skin, or a fallback skin taken from a chosen Minecraft username.

The mod is server-side only, so players join without installing anything. It is published for Fabric across 21 release versions, 1.20.2 – 26.2, and its code is open source under the MIT License. Public source code is available, and the latest Fabric file, 1.3.1, targets 26.2.