ClassicUO Web gives shard owners a browser-native path to reach players — no client installs, no manual patching on the player side. Your shard appears in the built-in server list, custom assets are delivered through a global CDN using efficient binary-delta patches, and the game connection is proxied over WebSocket so players connect through geographically distributed infrastructure without ever exposing your server IP. This guide introduces the key concepts and links you to the detailed references for each area.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.
Architecture overview
Understanding how ClassicUO Web works end-to-end will help you configure and troubleshoot your shard integration.WebAssembly client
The C# desktop ClassicUO client is compiled to WebAssembly and runs entirely in the browser. No plugin or download is required — a Chrome-like browser and a few gigabytes of free disk space are all a player needs.
Content CDN & patching
Assets are stored as content-addressable VCDIFF binary-delta patches on a global CDN. Players download only the chunks they are missing, and content is deduplicated across shards so the same file is never fetched twice.
Game proxy (WebSocket)
Direct TCP from a browser is not possible. ClassicUO Web bridges the gap with a WebSocket game proxy deployed on Fly.io across 30+ regions on an anycast address. The proxy authenticates players and hides your shard’s real IP.
Shard Management
Shard staff access a dedicated Shard Management portal to upload patches, publish content to the CDN, configure shard rules, manage the server list entry, and enable the WebIdentity packet.
Adding your shard to the server list
The shard application process is currently in BETA. Submit a shard application to request access.
Key features for shard owners
Custom asset patching
Upload your modified MUL or UOP files through the browser-based patcher. The system automatically converts UOP assets to MUL for smaller deltas (e.g. 90 MB → 2 MB), then publishes them to the CDN in one click.
Shard Rules
Control exactly which ClassicUO features are available to your players. Disable scripting, turn off the dress agent or friends list, and override default values for any game-profile option — all without shipping a custom client.
IP protection & DDOS resilience
Because all traffic routes through the game proxy, your shard’s real IP is never exposed to players. The anycast proxy address distributes attack surface across Fly.io’s entire network.
WebIdentity packet
Enable the WebIdentity packet in Shard Management to receive each player’s real IP through the proxy, solving IP-limit issues caused by multiple users sharing a regional proxy egress address.
Explore the guides
Patching
Step-by-step walkthrough for uploading your custom assets and publishing them to the CDN.
Shard Rules
Full reference for the ShardRules schema — scripting, feature flags, and profile option overrides.
Shard FAQ
Answers to common questions about the game proxy, IP handling, open-source status, and custom clients.
Modding Overview
Learn about the Typescript modding API available to shard owners for building custom client experiences.