Vanilla addons, each one loaded in our Vanilla client simulator so you know what works before you install it. Addons whose licence lets us share them install in one click from the launcher; every other addon links to its author. Our own Open Vanilla addons are marked Ours.
Made a Vanilla addon, or fixed one up for Vanilla Remastered? Upload it as a zip (10 MB at most). It waits in a review queue: we load it in the Vanilla client simulator, look for anything unsafe (chat sent on its own, other addons' saved data, os/io), and a moderator checks it and its licence before it is listed. We only host addons whose licence allows it (MIT, BSD, Apache-2.0, GPL, LGPL, MPL-2.0, Unlicense, CC0); for anything else, send us the author's link instead.
Making one? Vanilla Forge writes and checks addons for the game client, and runs them in a pretend client before you start the game.
The badges come from an automatic check: the addon is loaded in a simulated Vanilla client, through login and a few seconds of play. Works loaded clean; Partly loaded but uses parts of the client the simulator does not model (judge it in the game); Needs fixes showed errors; addons we may not host are not checked. Ratings, reviews and install counts are live from the realm; when it cannot be reached, the page shows the last snapshot and is read-only.