Properties Unicode Escape Sequences to JSON

Unicode Escapes in Properties Files

Java .properties files use ISO 8859-1 (Latin-1) encoding by default. To represent characters outside this range (CJK, Cyrillic, Arabic, emoji, etc.), they must be escaped using \uXXXX notation where XXXX is the Unicode code point in hexadecimal.

Example: Japanese i18n Resource Bundle

# messages_ja.properties
app.title=\u30c7\u30d9\u30ed\u30c3\u30d1\u30fc\u30c4\u30fc\u30eb\u30dc\u30c3\u30af\u30b9
app.description=\u7121\u6599\u306e\u30aa\u30f3\u30e9\u30a4\u30f3\u958b\u767a\u30c4\u30fc\u30eb
greeting.hello=\u3053\u3093\u306b\u3061\u306f
greeting.goodbye=\u3055\u3088\u3046\u306a\u3089
error.not_found=\u30da\u30fc\u30b8\u304c\u898b\u3064\u304b\u308a\u307e\u305b\u3093
error.server=\u30b5\u30fc\u30d0\u30fc\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3057\u307e\u3057\u305f

Decoded JSON Output

The converter automatically decodes all \uXXXX sequences:

{
  "app": {
    "title": "デベロッパーツールボックス",
    "description": "無料のオンライン開発ツール"
  },
  "greeting": {
    "hello": "こんにちは",
    "goodbye": "さようなら"
  },
  "error": {
    "notFound": "ページが見つかりません",
    "server": "サーバーエラーが発生しました"
  }
}

Why This Matters

Modern i18n systems (react-intl, next-intl, i18next) use JSON format for translation files. Converting from the legacy Java .properties format to JSON with proper Unicode decoding is an essential migration step. The tool handles:

• Standard BMP characters (\u0000 to \uFFFF)
• Mixed ASCII and Unicode text
• Multiple consecutive escapes