Migration Guide

This guide provides step-by-step instructions for migrating translation resources from other translation management systems to LingoTracker.

Overview
Before You Begin
Migrating from Transloco
Migrating from i18next
Migrating from Other Systems
Post-Migration Steps
Troubleshooting

Overview

What is Migration?

Migration is the process of importing existing translation resources from another system into LingoTracker. The import feature supports two migration workflows:

Direct Migration: Import translations directly using the migration strategy
Two-Step Migration: Export from source system, transform format, then import

Supported Source Formats

JSON: Flat or hierarchical structures (Transloco, i18next, etc.)
XLIFF: Industry standard format from CAT tools
Custom Formats: Transform to JSON or XLIFF first

What Gets Migrated

Translation keys and values (all locales)
Base locale values (source language)
Comments (if present in source format)
Tags (if present in source format)

What Doesn't Get Migrated

Translation history
Translator assignments
Review workflows
Custom metadata (not in standard formats)

Before You Begin

1. Initialize LingoTracker

Create a new LingoTracker project or ensure you have one initialized:

lingo-tracker init

Configure .lingo-tracker.json with your base locale and target locales:

{
  "baseLocale": "en",
  "locales": ["en", "es", "fr", "de"],
  "collections": {
    "Main": {
      "translationsFolder": "translations"
    }
  }
}

2. Backup Source Data

Always create a backup of your original translation files before migration:

# Copy your translation files to a backup location
cp -r ./src/i18n ./src/i18n.backup

If something goes wrong, restore with:

cp -r ./src/i18n.backup ./src/i18n

3. Choose Migration Strategy

LingoTracker's import feature has a dedicated migration strategy that:

Creates new resources when --create-missing is specified
Resolves Transloco-style key references ({{t('key')}})
Updates comments and tags when --update-comments / --update-tags are specified
Sets all imported translations to translated status

Tip: Always do a dry run first to preview what will be created before committing to the import:
lingo-tracker import --source en.json --locale en --strategy migration \
  --create-missing --dry-run

Migrating from Transloco

Transloco is Angular's internationalization library. LingoTracker provides specialized support for Transloco migrations.

After completing the steps below, follow the Post-Migration Steps to normalize resources, configure bundles, and test your application.

Source Format

Transloco typically uses one JSON file per locale:

src/assets/i18n/
├── en.json
├── es.json
├── fr.json
└── de.json

Example en.json (hierarchical):

{
  "common": {
    "buttons": {
      "ok": "OK",
      "cancel": "Cancel"
    }
  },
  "dashboard": {
    "title": "Dashboard",
    "welcome": "Welcome back"
  }
}

Step 1: Import Base Locale

Import the base locale first to create the resource structure. If you have multiple collections, add --collection <name>:

lingo-tracker import \
  --source ./src/assets/i18n/en.json \
  --locale en \
  --strategy migration \
  --create-missing \
  --update-comments \
  --update-tags \
  --verbose

Note: Importing into the base locale is only supported with the migration strategy. It creates resources with the base locale value set from the JSON values.

Step 2: Import Target Locales

Import each target locale:

# Import Spanish
lingo-tracker import \
  --source ./src/assets/i18n/es.json \
  --locale es \
  --strategy migration \
  --create-missing \
  --update-comments \
  --update-tags \
  --verbose

# Import French
lingo-tracker import \
  --source ./src/assets/i18n/fr.json \
  --locale fr \
  --strategy migration \
  --create-missing \
  --update-comments \
  --update-tags

# Import German
lingo-tracker import \
  --source ./src/assets/i18n/de.json \
  --locale de \
  --strategy migration \
  --create-missing \
  --update-comments \
  --update-tags

If your target locale files are missing base values, you can add them with a transformation script before importing. See Migrating from Other Systems > Generic JSON for an example transform.

Step 3: Handle Transloco References

If your Transloco files use references like {{t('other.key')}}, LingoTracker automatically resolves them during migration:

Before (with references):

{
  "greeting": "Hello",
  "welcome": "{{t('greeting')}}, welcome back!"
}

After (resolved):

{
  "greeting": "Hello",
  "welcome": "Hello, welcome back!"
}

This happens automatically with the migration strategy.

Step 4: Verify Migration

Check the import summary — the exact path is printed at the end of each import command output (typically {translationsFolder}/import-summary.md):

# Example — adjust path to match your translationsFolder config
cat translations/import-summary.md

Verify a few resources were created correctly:

cat translations/common/buttons/resource_entries.json

Step 5: Update Transloco Configuration

After migration, update your Transloco loader to use LingoTracker bundles:

Before:

loader: TranslocoHttpLoader  // Loads from src/assets/i18n

After:

// 1. Add bundle configuration to .lingo-tracker.json
{
  "bundles": {
    "transloco": {
      "bundleName": "{locale}",
      "dist": "./src/assets/i18n",
      "collections": "All"
    }
  }
}

// 2. Generate bundles
// Add to package.json:
{
  "scripts": {
    "prebuild": "lingo-tracker bundle"
  }
}

// 3. Transloco config stays the same
// Bundle files replace old i18n files

Migrating from i18next

i18next is a popular internationalization framework for JavaScript. LingoTracker can import i18next JSON files directly.

After completing the steps below, follow the Post-Migration Steps to normalize resources, configure bundles, and test your application.

Source Format

i18next typically organizes translations by namespace:

public/locales/
├── en/
│   ├── common.json
│   ├── dashboard.json
│   └── translation.json
├── es/
│   ├── common.json
│   ├── dashboard.json
│   └── translation.json
└── fr/
    ├── common.json
    ├── dashboard.json
    └── translation.json

Example en/common.json:

{
  "buttons": {
    "ok": "OK",
    "cancel": "Cancel"
  },
  "errors": {
    "required": "This field is required",
    "invalid": "Invalid input"
  }
}

Step 1: Combine Namespaces

i18next uses separate files per namespace. LingoTracker works with a single file per locale, so combine namespaces:

# Create migration directory
mkdir -p migration

# Combine English namespaces
node -e "
const fs = require('fs');
const common = JSON.parse(fs.readFileSync('./public/locales/en/common.json', 'utf8'));
const dashboard = JSON.parse(fs.readFileSync('./public/locales/en/dashboard.json', 'utf8'));
const translation = JSON.parse(fs.readFileSync('./public/locales/en/translation.json', 'utf8'));

const combined = {
  common,
  dashboard,
  translation
};

fs.writeFileSync('./migration/en.json', JSON.stringify(combined, null, 2));
console.log('Created migration/en.json');
"

Or create a more robust script:

// combine-namespaces.js
const fs = require('fs');
const path = require('path');

const localesDir = './public/locales';
const outputDir = './migration';

if (!fs.existsSync(outputDir)) {
  fs.mkdirSync(outputDir);
}

const locales = fs.readdirSync(localesDir);

for (const locale of locales) {
  const localePath = path.join(localesDir, locale);

  if (!fs.statSync(localePath).isDirectory()) continue;

  const combined = {};
  const namespaces = fs.readdirSync(localePath);

  for (const namespace of namespaces) {
    if (!namespace.endsWith('.json')) continue;

    const namespaceName = namespace.replace('.json', '');
    const content = JSON.parse(fs.readFileSync(path.join(localePath, namespace), 'utf8'));

    combined[namespaceName] = content;
  }

  fs.writeFileSync(
    path.join(outputDir, `${locale}.json`),
    JSON.stringify(combined, null, 2)
  );

  console.log(`Created migration/${locale}.json`);
}

Run the script:

node combine-namespaces.js

Step 2: Import Base Locale

Import the base locale (usually English). If you have multiple collections, add --collection <name>:

lingo-tracker import \
  --source ./migration/en.json \
  --locale en \
  --strategy migration \
  --create-missing \
  --update-comments \
  --update-tags \
  --verbose

Step 3: Import Target Locales

Import each target locale:

# Import Spanish
lingo-tracker import \
  --source ./migration/es.json \
  --locale es \
  --strategy migration \
  --create-missing \
  --update-comments \
  --update-tags

# Import French
lingo-tracker import \
  --source ./migration/fr.json \
  --locale fr \
  --strategy migration \
  --create-missing \
  --update-comments \
  --update-tags

Step 4: Update i18next Configuration

After migration, update your i18next configuration to use LingoTracker bundles:

Add bundle configuration (.lingo-tracker.json):

{
  "bundles": {
    "i18next": {
      "bundleName": "{locale}/translation",
      "dist": "./public/locales",
      "collections": "All"
    }
  }
}

Generate bundles:

lingo-tracker bundle

Update package.json:

{
  "scripts": {
    "prebuild": "lingo-tracker bundle",
    "dev": "lingo-tracker bundle && vite"
  }
}

Your i18next configuration stays the same - it will load from the generated bundle files.

Migrating from Other Systems

From JSON Files (Generic)

If your system uses JSON files in a custom format:

Step 1: Transform to LingoTracker Format

Create a transformation script to convert your format to LingoTracker's expected structure:

Flat structure with simple values:

{
  "app.title": "My App",
  "app.welcome": "Welcome",
  "buttons.ok": "OK"
}

Hierarchical with rich objects (recommended for migration):

{
  "app": {
    "title": {
      "value": "My App",
      "baseValue": "My App",
      "comment": "Application title"
    },
    "welcome": {
      "value": "Welcome",
      "baseValue": "Welcome"
    }
  },
  "buttons": {
    "ok": {
      "value": "OK",
      "baseValue": "OK"
    }
  }
}

Step 2: Import with Migration Strategy

lingo-tracker import \
  --source ./transformed-en.json \
  --locale en \
  --strategy migration \
  --create-missing

lingo-tracker import \
  --source ./transformed-es.json \
  --locale es \
  --strategy migration \
  --create-missing

From XLIFF Files

If your source system exports XLIFF files (common for CAT tools like SDL Trados, MemoQ, Smartling):

Step 1: Ensure XLIFF 1.2 Format

LingoTracker supports XLIFF 1.2. If you have XLIFF 2.0, convert it first:

# Using xliff-tool (install via npm)
npm install -g xliff-tool
xliff-tool convert --from xliff2 --to xliff es.xlf es-converted.xliff

Step 2: Import XLIFF Files

# Import each locale
lingo-tracker import \
  --source ./es.xliff \
  --locale es \
  --strategy migration \
  --create-missing \
  --verbose

XLIFF files include both source and target values, so LingoTracker automatically creates resources with proper base values.

From PO Files (gettext)

If your source system uses PO files (gettext format):

Step 1: Convert PO to JSON

Use a conversion tool like po2json:

npm install -g po2json

# Convert PO to JSON
po2json es.po es.json --format mf

Step 2: Transform to LingoTracker Format

// transform-po-json.js
const fs = require('fs');

const poJson = JSON.parse(fs.readFileSync('./es.json', 'utf8'));
const baseJson = JSON.parse(fs.readFileSync('./en.json', 'utf8'));

const transformed = {};

for (const [key, value] of Object.entries(poJson)) {
  // Skip metadata entries
  if (key === '') continue;

  // Create rich format with base value
  const dotKey = key.replace(/\//g, '.'); // Convert slashes to dots

  transformed[dotKey] = {
    value: value,
    baseValue: baseJson[key] || value
  };
}

fs.writeFileSync('./es-transformed.json', JSON.stringify(transformed, null, 2));

Step 3: Import

lingo-tracker import \
  --source ./es-transformed.json \
  --locale es \
  --strategy migration \
  --create-missing

From CSV Files

If you have translations in CSV format:

Step 1: Convert CSV to JSON

// csv-to-json.js
const fs = require('fs');
const csv = require('csv-parser');

const locales = ['es', 'fr', 'de'];
const results = {};

locales.forEach(locale => results[locale] = {});

fs.createReadStream('./translations.csv')
  .pipe(csv())
  .on('data', (row) => {
    const key = row.key;
    const baseValue = row.en;

    locales.forEach(locale => {
      if (row[locale]) {
        results[locale][key] = {
          value: row[locale],
          baseValue: baseValue
        };
      }
    });
  })
  .on('end', () => {
    locales.forEach(locale => {
      fs.writeFileSync(
        `./${locale}.json`,
        JSON.stringify(results[locale], null, 2)
      );
      console.log(`Created ${locale}.json`);
    });
  });

Expected CSV format:

key,en,es,fr,de
app.title,My App,Mi Aplicación,Mon Application,Meine App
buttons.ok,OK,Aceptar,OK,OK

Step 2: Import

lingo-tracker import --source ./es.json --locale es --strategy migration --create-missing
lingo-tracker import --source ./fr.json --locale fr --strategy migration --create-missing
lingo-tracker import --source ./de.json --locale de --strategy migration --create-missing

Post-Migration Steps

1. Verify Import Summary

The import command prints the summary file path at the end of its output. Open it to check each locale import:

# Path depends on your translationsFolder config — check the import output
cat translations/import-summary.md

Look for:

Resources imported count
Warnings (e.g., missing base values)
Errors (e.g., malformed keys)
ICU auto-fixes applied

2. Run Normalization

Ensure all resources have entries for all configured locales:

lingo-tracker normalize --all

This adds missing locale entries with the base value as a placeholder.

3. Review Missing Translations

Export resources with new or stale status to identify missing translations:

lingo-tracker export --format json --status new,stale --output ./review

If you have multiple collections, add --collection <name> to target a specific one.

4. Configure Bundles

Set up bundle generation for your framework:

{
  "bundles": {
    "app": {
      "bundleName": "{locale}",
      "dist": "./src/assets/i18n",
      "collections": "All"
    }
  }
}

Generate bundles:

lingo-tracker bundle

5. Update Build Scripts

Add bundle generation to your build pipeline:

{
  "scripts": {
    "prebuild": "lingo-tracker bundle",
    "build": "ng build",
    "dev": "lingo-tracker bundle && ng serve"
  }
}

6. Test Application

Start your application
Verify translations load correctly
Test language switching
Check for console errors
Verify ICU message format placeholders work

7. Remove Old Translation Files

Once migration is verified:

# Backup old files first
mv ./src/assets/i18n ./src/assets/i18n.old

# Generate fresh bundles
lingo-tracker bundle

# Test application thoroughly
# If everything works, remove backup
rm -rf ./src/assets/i18n.old

8. Update Version Control

Add LingoTracker files to version control:

# Add translations
git add translations/

# Add configuration
git add .lingo-tracker.json

# Optionally gitignore generated bundles
echo "src/assets/i18n/*.json" >> .gitignore

# Commit
git commit -m "feat: migrate to LingoTracker"

Troubleshooting

Import Fails: "Cannot create resource: base value not provided"

Cause: JSON file doesn't include base values for new resources.

Solution: Use rich JSON format with baseValue field:

{
  "app.title": {
    "value": "My App",
    "baseValue": "My App"
  }
}

Or import base locale first, then import target locales.

Import Warning: "Base value mismatch"

Cause: The baseValue in your import file differs from the existing base locale value in LingoTracker.

Effect: LingoTracker preserves the existing base value and warns you.

Solution: This is expected during migration. Review warnings to ensure base values are correct. If needed, update base values manually after migration.

Keys Not Created: Hierarchical conflict

Cause: A key exists as both a parent and a leaf. For example:

{
  "app": "My App",
  "app": {
    "title": "App Title"
  }
}

Solution: Restructure keys to avoid conflicts:

{
  "app": {
    "root": "My App",
    "title": "App Title"
  }
}

ICU Placeholders Not Working

Cause: Translators modified placeholder names during translation.

Effect: LingoTracker's ICU auto-fixer corrects common placeholder errors automatically.

Check: Review import summary's "ICU Auto-Fixes" section to see what was corrected.

Manual Fix: If auto-fix failed, edit the translation manually:

# Find the resource
cat translations/path/to/resource/resource_entries.json

# Edit the translation to fix placeholders

Duplicate Keys Warning

Cause: Same key appears multiple times in import file.

Effect: Last occurrence wins (matches JSON parsing behavior).

Solution: Remove duplicate keys from source file before import.

Missing Translations After Migration

Cause: Not all locales were imported, or some translations were empty in source.

Solution:

Run normalization: lingo-tracker normalize --all
Export missing translations: lingo-tracker export --status new --format xliff
Send to translators or translate manually
Import completed translations

Application Loads Old Translations

Cause: Browser cache or build cache serving old bundle files.

Solution:

Clear browser cache (hard refresh: Cmd+Shift+R or Ctrl+Shift+R)
Clear build cache: rm -rf dist/ .angular/cache/
Rebuild: npm run build
Verify bundle files in dist/ are up-to-date

Import Summary Shows Skipped Resources

Cause: Using wrong strategy or missing --create-missing. Default translation-service strategy doesn't create new resources.

Solution: Use --strategy migration --create-missing for migration imports:

lingo-tracker import --source file.json --locale es --strategy migration --create-missing

Summary

Migrating to LingoTracker involves:

Prepare source files (transform format if needed)
Dry run with --dry-run to preview what will be created
Import with --strategy migration --create-missing
Normalize to add missing locale entries
Configure bundles for your framework
Test thoroughly before removing old files

Quick Reference

# Migration workflow (base locale first, then target locales)
lingo-tracker import --source en.json --locale en --strategy migration \
  --create-missing --update-comments --update-tags
lingo-tracker import --source es.json --locale es --strategy migration \
  --create-missing --update-comments --update-tags
lingo-tracker import --source fr.json --locale fr --strategy migration \
  --create-missing --update-comments --update-tags

# Post-migration
lingo-tracker normalize --all
lingo-tracker bundle

# Verify (path printed at end of each import command)
cat translations/import-summary.md

For additional help:

Need Help? Open an issue at github.com/lingotracker/lingotracker/issues

Table of Contents​

Overview​

What is Migration?​

Supported Source Formats​

What Gets Migrated​

What Doesn't Get Migrated​

Before You Begin​

1. Initialize LingoTracker​

2. Backup Source Data​

3. Choose Migration Strategy​

Migrating from Transloco​

Source Format​

Step 1: Import Base Locale​

Step 2: Import Target Locales​

Step 3: Handle Transloco References​

Step 4: Verify Migration​

Step 5: Update Transloco Configuration​

Migrating from i18next​

Source Format​

Step 1: Combine Namespaces​

Step 2: Import Base Locale​

Step 3: Import Target Locales​

Step 4: Update i18next Configuration​

Migrating from Other Systems​

From JSON Files (Generic)​

Step 1: Transform to LingoTracker Format​

Step 2: Import with Migration Strategy​

From XLIFF Files​

Step 1: Ensure XLIFF 1.2 Format​

Step 2: Import XLIFF Files​

From PO Files (gettext)​

Step 1: Convert PO to JSON​

Step 2: Transform to LingoTracker Format​

Step 3: Import​

From CSV Files​

Step 1: Convert CSV to JSON​

Step 2: Import​

Post-Migration Steps​

1. Verify Import Summary​

2. Run Normalization​

3. Review Missing Translations​

4. Configure Bundles​

5. Update Build Scripts​

6. Test Application​

7. Remove Old Translation Files​

8. Update Version Control​

Troubleshooting​

Import Fails: "Cannot create resource: base value not provided"​

Import Warning: "Base value mismatch"​

Keys Not Created: Hierarchical conflict​

ICU Placeholders Not Working​

Duplicate Keys Warning​

Missing Translations After Migration​

Application Loads Old Translations​

Import Summary Shows Skipped Resources​

Summary​

Quick Reference​

Table of Contents

Overview

What is Migration?

Supported Source Formats

What Gets Migrated

What Doesn't Get Migrated

Before You Begin

1. Initialize LingoTracker

2. Backup Source Data

3. Choose Migration Strategy

Migrating from Transloco

Source Format

Step 1: Import Base Locale

Step 2: Import Target Locales

Step 3: Handle Transloco References

Step 4: Verify Migration

Step 5: Update Transloco Configuration

Migrating from i18next

Source Format

Step 1: Combine Namespaces

Step 2: Import Base Locale

Step 3: Import Target Locales

Step 4: Update i18next Configuration

Migrating from Other Systems

From JSON Files (Generic)

Step 1: Transform to LingoTracker Format

Step 2: Import with Migration Strategy

From XLIFF Files

Step 1: Ensure XLIFF 1.2 Format

Step 2: Import XLIFF Files

From PO Files (gettext)

Step 1: Convert PO to JSON

Step 2: Transform to LingoTracker Format

Step 3: Import

From CSV Files

Step 1: Convert CSV to JSON

Step 2: Import

Post-Migration Steps

1. Verify Import Summary

2. Run Normalization

3. Review Missing Translations

4. Configure Bundles

5. Update Build Scripts

6. Test Application

7. Remove Old Translation Files

8. Update Version Control

Troubleshooting

Import Fails: "Cannot create resource: base value not provided"

Import Warning: "Base value mismatch"

Keys Not Created: Hierarchical conflict

ICU Placeholders Not Working

Duplicate Keys Warning

Missing Translations After Migration

Application Loads Old Translations

Import Summary Shows Skipped Resources

Summary

Quick Reference