FOS Essentials Core — The free foundation for VRChat world tools Free, and installed through the VRChat Creator Companion. Every FOS tool sits on this one. On its own it is still worth having: it defuses the two UdonSharp traps that fail without a single error message, and gives you a Hub that tells you when your project is misconfigured — before you spend an evening hunting a bug that was never in your code. What it does - Registers your assemblies with UdonSharp, automatically. UdonSharp only compiles `Assembly-CSharp` and the assemblies explicitly declared to it. A behaviour placed in an assembly definition without that declaration is ignored by the compiler — no error, no warning. The component drops onto the object normally, and does nothing in game. - Creates the missing program assets. UdonSharp does not generate `UdonSharpProgramAsset` files, and without one a script cannot be added to a GameObject at all. The Core scans for them and creates them, on load and on demand. - A Hub that checks your project. Unity and SDK versions, registered assemblies, missing program assets, the FOS packs installed and what each of them requires. Every prefab of every installed pack is one click away from your scene. - A FOS banner on every component, with Discord and store buttons, and no editor code to write for it. - Editor interface in English, French, Spanish and German. - A runtime base class, `FOSBehaviour`: logging you can switch on per component, plus ownership and serialisation helpers that avoid the classic Udon mistakes. - A player registry rebuilt on join and leave rather than every frame, that any script can subscribe to. How to install 1. Open the VRChat Creator Companion → **Settings → Packages → Add Repository** 2. Paste `https://essentials.frenchoasis.studio/index.json` 3. Open your project and add FOS Essentials Core Updates then come through VCC like any other package — nothing to import again, and nothing to rewire. What you get: the Core package with its full source, README and changelog. Free, and free to update. Requirements: Unity 2022.3.22f1, VRChat Worlds SDK 3.10.4, UdonSharp. Built-in render pipeline. PC and Quest behave identically — there is no platform-specific code, and in Udon there could not be. Version: 1.3.0 The rest of the line. The same listing carries every FOS tool: Teleport, UI Culling, Mirror, Localization, Sync Doctor and Access — all free — alongside Tablet System and Lock Door System. Each installs the same way and pulls the Core in on its own.