langcodec

Universal localization tooling for real product workflows.

Convert, inspect, normalize, translate, annotate, and sync localization assets across Apple, XLIFF, Android, CSV, TSV, and Tolgee-backed pipelines.

CLI | Library | docs.rs | CLI Guide | Library Guide | Contributing

Why langcodec?

Most localization workflows are a pile of one-off scripts, format-specific tools, spreadsheet exports, and CI glue. langcodec gives you one Rust-native toolkit for the loop teams actually run:

• move between Apple, Android, and tabular formats without losing structure
• inspect stale, missing, or incomplete strings before they ship
• normalize files so diffs stay readable in review and CI
• draft translations with AI-backed providers
• generate better translator comments from real source usage
• sync .xcstrings catalogs with Tolgee without custom release scripts

Highlights

• Unified data model for singular and plural translations
• Read and write support for Apple .strings, Apple .xcstrings, Apple/Xcode .xliff, Android strings.xml, CSV, and TSV
• CLI commands for convert, diff, merge, sync, edit, normalize, view, stats, debug, translate, annotate, and Tolgee sync
• Config-driven AI workflows with langcodec.toml
• Rust library API for teams building custom localization pipelines

Quick Start

Install the CLI:

cargo install langcodec-cli

Use the library:

[dependencies]
langcodec = "0.11.0"

Try the workflow:

# Convert Apple strings to Android XML
langcodec convert -i Localizable.strings -o values/strings.xml

# Export an Apple/Xcode translation exchange file
langcodec convert -i Localizable.xcstrings -o Localizable.xliff --output-lang fr

# Import XLIFF back into an Xcode string catalog
langcodec convert -i Localizable.xliff -o Localizable.xcstrings

# Inspect work that still needs attention
langcodec view -i Localizable.xcstrings --status new,needs_review --keys-only

# Normalize catalogs in CI
langcodec normalize -i 'locales/**/*.{strings,xml,csv,tsv,xcstrings}' --check

# Draft translations into an existing string catalog
langcodec translate \
  --source Localizable.xcstrings \
  --source-lang en \
  --target-lang fr,de,ja \
  --provider openai \
  --model gpt-5.4

# Draft translations between single-language files too
langcodec translate \
  --source en.lproj/Localizable.strings \
  --target values-fr/strings.xml \
  --source-lang en \
  --target-lang fr \
  --provider openai \
  --model gpt-5.4

# Generate translator-facing comments from source usage
langcodec annotate \
  --input Localizable.xcstrings \
  --source-root Sources \
  --source-root Modules \
  --provider openai \
  --model gpt-5.4

# Annotate Apple .strings or Android XML inline
langcodec annotate \
  --input en.lproj/Localizable.strings \
  --source-root Sources \
  --provider openai \
  --model gpt-5.4

Packages

Package	What it is	Best for
langcodec	Rust library crate	Building custom localization tooling, validation, and conversions in Rust
langcodec-cli	Command-line interface	Day-to-day conversion, cleanup, translation, annotation, and sync workflows

Format Support

Format	Parse	Write	Convert	Merge	Plurals	Comments
Apple .strings	yes	yes	yes	yes	no	yes
Apple .xcstrings	yes	yes	yes	yes	yes	yes
Apple .xliff	yes	yes	yes	no	no	yes
Android strings.xml	yes	yes	yes	yes	yes	yes
CSV	yes	yes	yes	yes	no	no
TSV	yes	yes	yes	yes	no	no

AI Workflows

langcodec is built for app localization workflows, not just isolated text snippets. translate and annotate can be driven from a shared langcodec.toml, use supported providers such as OpenAI, Anthropic, and Gemini, and scale from single-language files or .xcstrings catalogs to config-driven runs across larger repos.

[openai]
model = "gpt-5.4"

[translate]
concurrency = 4
use_tolgee = true

[translate.input]
source = "locales/Localizable.xcstrings"
lang = "en"
status = ["new", "stale"]

[translate.output]
lang = ["fr", "de"]
status = "translated"

[annotate]
input = "locales/Localizable.xcstrings"
source_roots = ["Sources", "Modules"]
concurrency = 4

Then run:

langcodec translate
langcodec annotate
langcodec tolgee pull

For deeper CLI examples, head to langcodec-cli/README.md.

Rust API

use langcodec::{Codec, convert_auto};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    convert_auto("Localizable.strings", "strings.xml")?;

    let mut codec = Codec::new();
    codec.read_file_by_extension("Localizable.xcstrings", None)?;

    for language in codec.languages() {
        println!("{language}");
    }

    Ok(())
}

The library is a good fit if you want to build custom pipelines, validate assets in CI, or work with a consistent representation instead of format-specific parsers.

Documentation

• CLI guide
• Library guide
• Contribution guide
• Project roadmap

License

MIT