Solving JSON i18n Translation Failures with Localizejson

Why ChatGPT breaks your JSON i18n files (and what I built to fix it)

Standard LLMs like ChatGPT often fail to distinguish between translatable strings and immutable code structures in JSON files. This results in corrupted placeholders like {name} becoming “nom” and keys being translated, causing immediate application crashes.

Why This Matters

In technical reality, i18n files require strict structural integrity where keys and variable placeholders must remain untouched to match codebase references. While LLMs are optimized for linguistic fluidity, they lack the deterministic logic needed to preserve nested JSON structures and specific formatting tokens like %d or {{variable}}, often leading to silent production failures.

Key Insights

• LLMs prioritize linguistic translation over structural integrity, often translating internal keys like “not_found” to “non_trouvé”.
• Standard placeholders such as {count} or %d are frequently omitted or translated, causing runtime errors in interpolation functions.
• Manual correction of AI-translated i18n files can take 20 minutes for tasks that should be completed in 30 seconds.
• Localizejson ensures all nested objects and arrays are handled correctly while guaranteeing placeholder survival.
• The tool is currently free and requires no signup for processing localized JSON files.

Working Examples

Input JSON file with nested structures and multiple placeholder types.

{
  "welcome": "Welcome back, {name}!",
  "messages": "You have {count} new messages",
  "dashboard": {
    "title": "Dashboard",
    "stats": "{count} active users",
    "growth": "{percentage}% growth"
  },
  "errors": {
    "not_found": "Page not found",
    "rate_limit": "Wait %d seconds"
  }
}

Correctly translated French output with preserved keys and placeholders.

{
  "welcome": "Bon retour, {name} !",
  "messages": "Vous avez {count} nouveaux messages",
  "dashboard": {
    "title": "Tableau de bord",
    "stats": "{count} utilisateurs actifs",
    "growth": "{percentage}% de croissance"
  },
  "errors": {
    "not_found": "Page introuvable",
    "rate_limit": "Patientez %d secondes"
  }
}

Practical Applications

• Use case: Developers using Localizejson to translate nested i18n files while keeping {percentage} and %d tokens intact.
• Pitfall: Using raw ChatGPT prompts to translate JSON, which leads to keys being modified and subsequent ‘key not found’ errors in the application.

References:

• https://localizejson.lovable.app
• https://dev.to/ardam_afzal/hy-chatgpt-breaks-your-json-i18n-files-and-what-i-built-to-fix-it-2ao