xlf-sync

📝 Read the article: The Missing Piece in Angular i18n

The definitive CLI tool for synchronizing Angular XLIFF (1.2 & 2.0) locale files.

xlf-sync is a robust, production-ready utility designed to solve the persistent challenge of Angular i18n management: keeping your locale files (messages.<locale>.xlf) in perfect sync with your source file (messages.xlf), without data loss or corruption.

It is built to integrate seamlessly into professional workflows, supporting both local development and strict CI/CD pipelines.

🌐 Visit the Official Landing Page & Documentation

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🚀 Why xlf-sync?

If you are coming from xliffmerge or ng-extract-i18n-merge, you'll find xlf-sync to be a modern, faster, and more reliable alternative.

Feature	xlf-sync	xliffmerge	ng-extract-i18n-merge
XLIFF 1.2 & 2.0	✅ Yes	✅ Yes	⚠️ Partial
Metadata Preservation	✅ Absolute	⚠️ Limited	⚠️ Limited
Visual Dashboard	✅ Yes	❌ No	❌ No
Zero Data Loss	✅ Guaranteed	⚠️ Risky	✅ Yes
Active Maintenance	✅ Active	❌ Legacy	✅ Active

Tip

Migration follows a similar flow: Simply point xlf-sync to your source and locale files. It will automatically detect your XLIFF version and merge without stripping your approved translations or translator notes.

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✨ Key Features

• 🔄 Full Synchronization: Automatically adds missing keys from messages.xlf to all your locale files.
• 🧠 Metadata Preservation: Preserves all notes, context groups, and custom attributes (e.g., approved="yes") during sync. Zero data loss.
• 🛡️ Data Safety: Never overwrites existing translations. Your work is safe.
• 🧬 Multi-Version Support: Seamlessly handles XLIFF 1.2 and 2.0 in the same project. It auto-detects the version per file.
• 🧹 Auto-Sorting: Reorders translations in locale files to match the source file's order, ensuring clean and readable diffs.
• 💀 Graveyard Mode: Optionally moves obsolete keys to a separate "graveyard" file instead of deleting them, preserving historical work.
• 🤖 CI/CD Ready: Dedicated check command with strict exit codes for your build pipelines.
• ✨ Pretty Printing: Normalizes XML formatting across all files, eliminating "dirty" diffs from other tools.

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📦 Installation

Install globally or as a dev dependency in your project:

npm install -D xlf-sync

npx xlf-sync --help

🎮 How it looks

$ npx xlf-sync sync

  xlf-sync v1.3.7
  --------------------------------------------------
  ✔ messages.xlf parsed (142 keys)
  ✔ messages.el.xlf synced (+12 new, -3 obsolete)
  ✔ messages.de.xlf synced (+12 new, -3 obsolete)
  ✔ messages.fr.xlf synced (+12 new, -3 obsolete)
  --------------------------------------------------
  ✨ Done! Your locale files are in perfect sync.

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📂 Configuration

You can avoid passing command-line arguments every time by creating an xlf-sync.json (or xlf-sync.config.json) file in your project root.

Example xlf-sync.json

{
  "source": "src/locale/messages.xlf",
  "locales": "src/locale/messages.*.xlf",
  "sync": {
    "newTarget": "todo",
    "obsolete": "mark",
    "dryRun": false
  },
  "check": {
    "failOnMissing": true,
    "verbose": true
  }
}

All Configuration Options

Option	JSON Key	Type	Description
Global	source	string	Path to source messages.xlf
	locales	string	Glob for locale files
Sync	sync.newTarget	string	todo | empty | source
	sync.obsolete	string	delete | mark | graveyard
	sync.graveyardFile	string	Path pattern for graveyard files
	sync.failOnMissing	boolean	Exit non-zero on missing targets
	sync.dryRun	boolean	Do not write files
Check	check.failOnMissing	boolean	Exit non-zero on missing targets
	check.failOnObsolete	boolean	Exit non-zero on obsolete keys
	check.failOnAdded	boolean	Exit non-zero on un-synced keys
	check.newTarget	string	todo | empty | source (for diff only)
	check.verbose	boolean	Print missing keys list

Tip

Precedence: Command Line Flags > xlf-sync.json > Default Values.

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🚀 Usage

1. The sync Command

The core command to update your locale files. It reads the source file and updates all target locale files found by the glob pattern.

# Basic usage
npx xlf-sync sync \
  --source src/locale/messages.xlf \
  --locales "src/locale/messages.*.xlf"

Sync Options

Option	Default	Description
--source <path>	src/locale/messages.xlf	Path to the source XLIFF file generated by ng extract-i18n.
--locales <glob>	src/locale/messages.*.xlf	Glob pattern to find your target locale files (e.g., src/locale/*.xlf).
--new-target <mode>	todo	Strategy for new keys: • todo: Fills target with TODO. • empty: Leaves target empty. • source: Copies source text to target.
--obsolete <mode>	mark	Strategy for removed source keys: • mark: Keeps key with state="obsolete" (or prefix). • delete: Permanently removes the key. • graveyard: Moves key to a separate file (see below).
--graveyard-file <pattern>	src/locale/_obsolete.{locale}.xlf	Pattern for the output "graveyard" file. Used only if --obsolete graveyard. {locale} is replaced dynamically.
--fail-on-missing	false	Exits with error (code 1) if any keys are missing translations. Useful if you want to enforce 100% translation coverage during sync.
--dry-run	false	Simulates the operation without writing changes to disk.

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2. The report Command

Generates a detailed console report about the translation coverage for each locale file. Useful for getting a quick overview of work remaining.

npx xlf-sync report --source src/locale/messages.xlf --locales "src/locale/messages.*.xlf"

Output Example:

┌────────┬─────┬──────┬────────────┬─────────┬────────┬───────┐
│ Locale │ XLF │ Keys │ Translated │ Pending │ % Cov  │ Words │
├────────┼─────┼──────┼────────────┼─────────┼────────┼───────┤
│ de     │ 2.0 │ 120  │ 115        │ 5       │ 95.8%  │ 432   │
│ fr     │ 2.0 │ 120  │ 40         │ 80      │ 33.3%  │ 150   │
└────────┴─────┴──────┴────────────┴─────────┴────────┴───────┘

Report Options

Option	Default	Description
--source <path>	src/locale/messages.xlf	Path to the source XLIFF file.
--locales <glob>	src/locale/messages.*.xlf	Glob pattern for target locale files.

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3. The dashboard Command

Generates a modern, standalone HTML dashboard to visualize your translation progress with beautiful charts, tables, and an interactive translation matrix.

npx xlf-sync dashboard --out report.html

Features:

• 📊 Visual Statistics Cards: Overview of locales, total keys, translated count, and pending translations
• 📈 Coverage Progress Bars: Per-locale translation progress with percentage indicators
• 🔍 Translation Matrix: Interactive table showing which keys exist in each locale
  • ✅ Green checkmark for translated keys
  • ❌ Red X for missing translations
  • Search bar to filter by key ID
• 🎨 Modern UI: Built with Tailwind CSS and Alpine.js for a premium, responsive experience
• 📱 Mobile-Friendly: Fully responsive design that works on all devices

Dashboard Options

Option	Default	Description
--source <path>	src/locale/messages.xlf	Path to the source XLIFF file.
--locales <glob>	src/locale/messages.*.xlf	Glob pattern for target locale files.
--out <path>	xlf-report.html	Path where the HTML file will be saved.

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4. The check Command

A read-only command designed for Continuous Integration (CI) pipelines. It verifies the state of your translations without modifying any files.

# Check if files are in sync
npx xlf-sync check --fail-on-missing

Check Options

Option	Default	Description
--source <path>	src/locale/messages.xlf	Path to the source XLIFF file.
--locales <glob>	src/locale/messages.*.xlf	Glob pattern for target locale files.
--verbose	false	Lists exactly which keys are missing or obsolete for each locale.
--fail-on-missing	false	CI Failure Condition: Fail if any translation targets are missing or empty.
--fail-on-obsolete	false	CI Failure Condition: Fail if obsolete keys exist in locale files.
--fail-on-added	false	CI Failure Condition: Fail if new keys exist in source that haven't been synced to locales yet.

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📚 Advanced Workflows

Keeping Files Clean (Graveyard Mode)

For large, long-lived projects, we recommend the Graveyard Strategy. Instead of cluttering your main files with obsolete keys or deleting them immediately (and losing work), this mode moves them to a separate file.

npx xlf-sync sync --obsolete graveyard

Result:

• messages.fr.xlf: Contains only active, valid translations.
• _obsolete.fr.xlf: Contains all retired keys. You can restore them later if needed.

Standard CI/CD Pipeline

Add this step to your Pull Request validation workflow to ensure no developer merges broken translations:

- name: Verify i18n Sync
  run: npx xlf-sync check --fail-on-missing --fail-on-added --verbose

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🛠️ Supported Formats

Format	Support Level
XLIFF 1.2	Legacy Angular projects. Supported fully.
XLIFF 2.0	Modern Angular default. Supported fully.
Hybrid	Mixed version projects are detecting and handled automatically per file.

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🤝 Contributing

We welcome contributions! Whether it's bug reports, feature requests, or code contributions, your help is appreciated.

Please read our Contributing Guidelines to get started.

Quick ways to contribute:

• ⭐ Star the project on GitHub
• 🐛 Report bugs
• 💡 Suggest features
• 🔧 Submit pull requests

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📄 License

MIT © Anastasios Theodosiou