Hytale UI Modding

Hytale Native UI Modding Skill

Use this skill for Hytale's native .ui system and the server-side Java UI API.

Important: use native UI only. Do not use HyUI.

Quick start

1. Read the architecture overview first. See references/overview.md.
2. Put .ui files under src/main/resources/Common/UI/Custom/.
3. Import Common.ui when you want shared styles and components. See references/common-styling.md.
4. Build layout with Anchor, Padding, and LayoutMode. See references/layout.md.
5. Use markup patterns like named expressions, templates, and translations. See references/markup.md.
6. Bind UI events with UIEventBuilder and always sendUpdate after handling events. See references/java-api.md and references/events.md.
7. For assets, use @2x.png and set IncludesAssetPack in manifest. See references/assets-and-packaging.md.
8. To attach a HUD to an item (shown when held/active), use the item JSON HudUI field. See references/item-hud-ui.md.
9. For translation keys and localized runtime strings, check references/translations.md.
10. If something fails at runtime, check references/troubleshooting.md.

Reference library

• references/INDEX.md
• references/overview.md
• references/common-styling.md
• references/layout.md
• references/markup.md
• references/type-documentation.md
• references/java-api.md
• references/anchor-ui.md
• references/events.md
• references/assets-and-packaging.md
• references/item-hud-ui.md
• references/translations.md
• references/examples.md
• references/troubleshooting.md

Project conventions

• .ui base path: Common/UI/Custom/. Relative paths inside .ui are resolved from the file location.
• Use %translation.key in .ui and add the key to the language files under src/main/resources/Server/Languages.
• Use MultipleHUD for multiple HUDs per player. Do not rely on a single CustomUIHud instance.
• Item HUD UIs are asset-driven: declare them in item JSON via the HudUI array field. No server-side Java is needed to show/hide them — the client manages their lifecycle automatically when the item is active.

Official documentation

• https://hytalemodding.dev/en/docs/official-documentation/custom-ui/common-styling
• https://hytalemodding.dev/en/docs/official-documentation/custom-ui/layout
• https://hytalemodding.dev/en/docs/official-documentation/custom-ui/markup
• https://hytalemodding.dev/en/docs/official-documentation/custom-ui/type-documentation

Notes on recent doc updates

• The official type documentation is a generated index. Use it when you need the exact property name, type, or enum values for an element.
• Common.ui is the preferred source for cohesive styling. Import it and reference styles instead of duplicating them.
• Added in server 2026.02.26-7681d338c: Item HUD UI support. Items can now declare .ui overlays in their JSON HudUI field that the client renders automatically when the item is held/active. See references/item-hud-ui.md.
• IntelliJ IDEA plugin for .ui file syntax highlighting, color picking, and code completion: https://plugins.jetbrains.com/plugin/29783-hytale-ui-support
• TabNavigation UI element documentation has been updated with examples and known issues. See the official type docs for current TabNavigation behavior. Items can now declare .ui overlays in their JSON HudUI field that the client renders automatically when the item is held/active. See references/item-hud-ui.md.