ClassicUO Web brings the full Ultima Online experience to your browser. Powered by WebAssembly, it runs the ClassicUO desktop client natively in Chrome — complete with a built-in Web Assistant, TypeScript scripting, modern UI components, and automatic asset patching. Players connect in seconds; shard owners get powerful tools to customize the experience.Documentation Index
Fetch the complete documentation index at: https://mintlify.com/ClassicUO/classicuo-web/llms.txt
Use this file to discover all available pages before exploring further.
Quick Start
Go from a new tab to in-game in minutes. Learn how to find a shard, log in with Discord, and start playing.
Features
Explore cloud-synced profiles, modern grid containers, autoloot, action bar, chat, and more.
Shard Owners
Add your shard to the server list, upload custom assets, and configure rules for your players.
Scripting API
Automate gameplay with TypeScript or visual Blockly scripts using the built-in scripting engine.
What is ClassicUO Web?
ClassicUO Web is the browser-based version of the ClassicUO Ultima Online client, compiled to WebAssembly and delivered over a global CDN. It replaces the traditional download-and-install flow with a one-click experience — visit a URL, log in with Discord, and you’re in the game.No Installation
Runs entirely in Chrome. Game files are downloaded once and cached locally in your browser.
Always Up to Date
Asset patches are automatically applied on launch via binary-delta diffs. No manual updates needed.
Cloud Synced
Profiles, macros, scripts, and hotkeys sync across every device you log into.
Modern UI
React-powered overlays replace dated UO gumps with grid containers, tabbed chat, tooltips, and more.
Scripting
TypeScript and visual scripting built in. Shard owners can enable, restrict, or disable it entirely.
Shard Modding
Build custom React UI mods with the
@classicuo/modding SDK, loaded per-shard at runtime.Getting Started
Open Chrome
ClassicUO Web requires a Chromium-based browser (Chrome, Edge, Brave). Firefox is not supported.
Browse the Server List
Visit play.classicuo.org to find a free shard or try the retail servers at retail.classicuo.org.
Log in with Discord
Authentication uses Discord to keep the service secure and sync your settings. No personally identifiable information is collected beyond your Discord username and ID.
For Shard Owners
ClassicUO Web provides first-class tools for running your shard on the platform.Patching Guide
Upload custom MUL/UOP assets to the CDN using the Shard Management tool and the diff-tool CLI.
Shard Rules
Control which client features your players can access — disable scripting, lock game options, set defaults.
Modding SDK
Build React-based UI mods with
@classicuo/modding. Mount custom gumps, listen to game events, interact with the client.Shard Owners FAQ
Common questions about the server list, IP proxying, WebIdentity packets, and the game proxy architecture.