fvtt-localization

# Foundry VTT Localization

**Domain:** Foundry VTT Module/System Development
**Status:** Production-Ready
**Last Updated:** 2026-01-05

## Overview

Foundry VTT uses JSON language files for internationalization. All user-facing text should be localized to support translation.

### When to Use This Skill

- Creating language files for modules/systems
- Using localize/format in JavaScript code
- Adding localization to templates
- Following naming conventions for translatable strings
- Handling pluralization and interpolation

## Language File Structure

### Basic Format

```json
{
  "MYMODULE.Title": "My Module",
  "MYMODULE.Settings.Enable": "Enable Feature",
  "MYMODULE.Settings.EnableHint": "Turn this feature on or off",
  "MYMODULE.Dialog.Confirm": "Are you sure?",
  "MYMODULE.Button.Save": "Save",
  "MYMODULE.Button.Cancel": "Cancel"
}
```

### Namespace Convention

Use your package ID as prefix to avoid conflicts:

```json
{
  "MYSYSTEM.Actor.HP": "Hit Points",
  "MYSYSTEM.Actor.AC": "Armor Class",
  "MYSYSTEM.Item.Weight": "Weight"
}
```

### Document Type Labels

```json
{
  "TYPES": {
    "Actor": {
      "character": "Character",
      "npc": "Non-Player Character",
      "vehicle": "Vehicle"
    },
    "Item": {
      "weapon": "Weapon",
      "armor": "Armor",
      "spell": "Spell"
    }
  }
}
```

## Manifest Registration

### module.json / system.json

```json
{
  "id": "my-module",
  "languages": [
    {
      "lang": "en",
      "name": "English",
      "path": "lang/en.json"
    },
    {
      "lang": "es",
      "name": "Español",
      "path": "lang/es.json"
    },
    {
      "lang": "fr",
      "name": "Français",
      "path": "lang/fr.json"
    }
  ]
}
```

### Language Codes

Use ISO 639-1 (2-letter) or ISO 639-2 (3-letter) codes:
- `en` - English
- `es` - Spanish
- `fr` - French
- `de` - German
- `ja` - Japanese
- `zh` - Chinese

## JavaScript API

### game.i18n.localize()

Simple string lookup:

```javascript
const title = game.i18n.localiz