config.json

{
  "$schema": "node_modules/@thomasfarineau/anvil/src/client/config.schema.json",
  "identifier": "com.mycompany.launcher",
  "app_name": "My Launcher",
  "data_folder": ".my-launcher",
  "java_version": 21,
  "logo": "logo.svg",
  "session": "none",
  "microsoft-client-id": "",
  "update_url": "",
  "target": "dist",
  "window": {
    "decorations": true,
    "resizable": true,
    "width": 1000,
    "height": 660,
    "shadow": true,
    "transparent": false,
    "devtools": true
  },
  "instances": [
    {
      "id": "survival",
      "name": "Survival",
      "mc_version": "1.21.4"
    },
    {
      "id": "modded",
      "name": "Modded",
      "mc_version": "1.21.4",
      "loader": "fabric",
      "loader_version": "0.16.9",
      "mods": [
        {
          "name": "Sodium",
          "url": "https://cdn.modrinth.com/data/AANobbMI/versions/.../sodium-fabric-0.6.5.jar"
        }
      ]
    }
  ]
}

Field reference

Field	Type	Description
identifier	string	Reverse-domain app identifier (e.g. com.mycompany.launcher)
app_name	string	App name shown in the native window and UI
data_folder	string	Sub-folder in %APPDATA% / ~/Library for game data
java_version	17 | 21	Java version to download automatically
logo	string	Path to the logo (relative to src/) — .svg or .png, auto-converted to app icon
session	"none" | "microsoft" | "custom" | "anvil-session"	Authentication mode — see Session and Anvil Server
microsoft-client-id	string	Microsoft Entra application ID required by the "microsoft" session
update_url	string	URL of the update manifest (leave empty to disable)
target	string	Output folder for compiled executables (e.g. dist)
window	object	Native launcher window settings
window.decorations	boolean	Show the native title bar
window.resizable	boolean	Allow the user to resize the window
window.width	integer	Initial launcher width in logical pixels (minimum 800)
window.height	integer	Initial launcher height in logical pixels (minimum 520)
window.shadow	boolean	Show the native window shadow
window.transparent	boolean	Use a transparent native window background
window.devtools	boolean	Enable or disable webview developer tools during npm run dev
instances	array	List of available Minecraft instances (ignored when anvil-server is set)
anvil-server	string	Base URL of an anvil-server: the launcher fetches its enabled instances from it at startup
anvil-key	string	API key generated in the anvil-server web UI — required to query the server

Instance fields

Field	Type	Description
id	string	Unique identifier (used as the folder name)
name	string	Label shown on the play button
mc_version	string	Minecraft version (e.g. "1.21.4")
loader	"fabric" | "forge" | "neoforge" | "quilt"	Mod loader (optional)
loader_version	string	Mod loader version (e.g. "0.16.9")
server_ip	string	Server IP for auto-connect on launch
server_port	number	Server port (default: 25565)
mods	array	Mods downloaded into the instance — see Mods per instance
files	array	Extra files ({path, url}) deployed into the instance folder at setup — usually provided by an anvil-server

Next steps

• Mods per instance
• Session
• Anvil Server