XCStrings Translator

Translate Apple's Localizable.xcstrings files using AI. Supports Claude, GPT, and Gemini.

xcstrings translate Localizable.xcstrings -l fr,es,it,ja,ko

Features

• Multi-provider - Choose Claude, GPT, or Gemini based on cost/quality needs
• Context-aware - Uses existing translations to understand meaning and tone
• Format-safe - Preserves %@, %lld, %1$@ and other specifiers
• 35+ languages - All major App Store locales
• Recursive - Point at a directory to translate every nested .xcstrings file
• Cost estimation - Preview costs before translating
• Validation - Detect missing translations and format mismatches

Quick Start

# Install
pip install xcstrings-translator

# Set API key (pick one)
export ANTHROPIC_API_KEY=sk-...   # Claude
export OPENAI_API_KEY=sk-...      # GPT
export GOOGLE_API_KEY=...         # Gemini
export OPENROUTER_API_KEY=sk-or-... # OpenRouter (any vendor)

# Translate
xcstrings translate Localizable.xcstrings -l fr,de,ja

Models

Model	Provider	Cost/1M tokens	Best for
haiku	Anthropic	$1 in / $5 out	Fast iteration
sonnet	Anthropic	$3 in / $15 out	Recommended (default)
opus	Anthropic	$5 in / $25 out	Highest quality
gpt-5.4-nano	OpenAI	$0.20 in / $1.25 out	Cheapest
gpt-5.4	OpenAI	$2.50 in / $15 out	Quality
gpt-5.5	OpenAI	$5 in / $30 out	Flagship
gemini-3.5-flash	Google	$1.50 in / $9 out	Fast & balanced
gemini-3.1-pro	Google	$2 in / $12 out	Quality

Older aliases still work: gpt-5, gpt-5-mini, gpt-5-nano, o3, o4-mini, gemini-2.5-pro/flash, gemini-2.0-flash.

xcstrings translate input.xcstrings -l fr -m haiku        # fast/cheap
xcstrings translate input.xcstrings -l fr -m sonnet       # balanced (default)
xcstrings translate input.xcstrings -l fr -m gpt-5.4-nano # cheapest

OpenRouter

Route through OpenRouter to reach any vendor with one key. Set OPENROUTER_API_KEY, then pass an openrouter:vendor/model string or a shorthand alias:

Alias	Model
or-opus, or-sonnet, or-haiku	Anthropic Claude (Opus 4.8 / Sonnet 4.6 / Haiku 4.5)
or-gpt-5.5, or-gpt-5.4, or-gpt-5.4-mini, or-gpt-5.4-nano	OpenAI GPT-5.5 / 5.4 family
or-gpt-5, or-gpt-5-mini, or-gpt-5-nano	OpenAI GPT-5 family
or-gemini-3.5-flash, or-gemini-3.1-pro, or-gemini-3-flash	Google Gemini 3.x
or-gemini-pro, or-gemini-flash	Google Gemini 2.5 Pro / Flash

xcstrings translate input.xcstrings -l fr -m openrouter:anthropic/claude-sonnet-4.6
xcstrings translate input.xcstrings -l fr -m or-gpt-5.4-nano

Cost estimates for openrouter:* models are fetched live from OpenRouter's public model catalog (cached ~24h under ~/.cache/xcstrings-translator/), so any model — even brand-new ones — gets accurate pricing in estimate/--dry-run. Pass --no-fetch to skip the network and use cached/static prices only.

Commands

Command	Description
translate	Translate to specified languages
estimate	Preview cost without translating
info	Show file stats and coverage
validate	Check for issues
languages	List all 35+ supported languages

Usage Examples

# Translate to multiple languages
xcstrings translate Localizable.xcstrings -l fr,es,it,de,ja

# Translate every .xcstrings under a project directory (recursive; asks first)
xcstrings translate ./MyApp -l fr,es,it
xcstrings translate ./MyApp --fill-missing -y   # skip the confirmation prompt

# Estimate cost first
xcstrings translate Localizable.xcstrings -l fr,es,it --dry-run

# Use faster model
xcstrings translate Localizable.xcstrings -l fr -m haiku

# Parallel requests (faster for large files)
xcstrings translate Localizable.xcstrings -l fr,es -c 32

# Save to different file
xcstrings translate input.xcstrings -l fr -o translated.xcstrings

# Fill missing translations only
xcstrings translate Localizable.xcstrings --fill-missing

# Check translation coverage
xcstrings info Localizable.xcstrings

# Validate format specifiers
xcstrings validate Localizable.xcstrings

App Context

Provide context for better translations. Create context.md next to your xcstrings file:

# My Fitness App

A workout tracking app for athletes.

Tone: Motivational, energetic.
Use informal "you" (du/tu).

Or pass directly:

xcstrings translate input.xcstrings -l fr --context "A fitness app with motivational tone"

Python API

from xcstrings_translator import XCStringsFile, XCStringsTranslator

# Load
xcstrings = XCStringsFile.from_file("Localizable.xcstrings")

# Translate
translator = XCStringsTranslator(model="sonnet")
xcstrings = translator.translate_file(xcstrings, ["fr", "es", "it"])

# Save
xcstrings.to_file("Localizable.xcstrings")

# Stats
print(f"Translated: {translator.stats.translated}")
# Rates below are sonnet's ($3 in / $15 out per 1M tokens); adjust for your model.
print(f"Cost: ${translator.stats.input_tokens * 3 / 1e6 + translator.stats.output_tokens * 15 / 1e6:.2f}")

Supported Languages

European: en, de, fr, es, it, pt, pt-BR, pt-PT, nl, pl, sv, da, nb, fi, cs, sk, hu, ro, bg, el, sq, uk, ru, tr

Asian: ja, ko, zh-Hans, zh-Hant, th, vi, id, ms, hi

Middle Eastern: ar, he

Other: ca, eu

Options

Option	Description	Default
-l, --languages	Target language codes	Required
-m, --model	AI model	sonnet
-o, --output	Output file	Overwrites input
-b, --batch-size	Strings per API call	25
-c, --concurrency	Parallel requests	32
--context	App description	context.md
--overwrite	Replace existing	false
--dry-run	Estimate only	false
-f, --fill-missing	Auto-detect languages	false
-y, --yes	Skip confirmation for directory runs	false

Troubleshooting

"Unsupported language" - Use Apple codes: zh-Hans not zh-CN, pt-BR not pt_BR

Format mismatch - Run xcstrings validate to find issues

API errors - Check correct key is set for your model

Contributing

Contributions are welcome! See CONTRIBUTING.md for dev setup, tests, and the release process. Please also review our Code of Conduct. To report a security issue, see SECURITY.md.

License

MIT

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Made with ❤️ by Justin Lanfermann