inlang

The open project file format for localization (i18n).

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Inlang is an open project file format for localization.

An .inlang project is canonically a single binary file: a SQLite database with version control via lix. Like .sqlite for relational data, .inlang packages localization data into one file that tools can share.

It is not another i18n library, message syntax, translation app, or SaaS backend. It gives editors, CLIs, IDE extensions, runtimes, and coding agents one shared place to read and write localization data.

The @inlang/sdk is the reference implementation for reading and writing .inlang projects.

.inlang is the canonical project format. Plugins import and export formats like JSON, ICU MessageFormat v1, i18next, and XLIFF for compatibility with existing translation files and runtimes. Version control via lix adds file-level history, merging, and change proposals to .inlang projects.

Messages, variants, and locale data live in the .inlang database. External translation files such as messages/en.json are compatibility files outside project.inlang/, connected through plugins.

project.inlang                  # canonical single binary file

For Git repositories, the binary file can be unpacked into a directory of plain files so changes can be reviewed alongside code. The packed file is the canonical format; the unpacked directory is the Git-friendly representation.

project.inlang/
├── settings.json               # locales, plugins, file patterns; kept in Git
├── .gitignore                  # generated; ignores everything except settings.json
├── README.md                   # generated; explains this folder to coding agents
├── .meta.json                  # generated SDK metadata
└── cache/                      # plugin cache, created when plugins are loaded

The problem

Common translation files like JSON, YAML, ICU, or XLIFF are good at storing messages. But they do not describe the whole localization project.

Once multiple tools need to read and write the same project, plain translation files start to miss important information:

• CRUD operations instead of custom parsing
• Search and reports across locales, variants, and metadata
• Version control via lix
• One shared file that editors, CI, and runtimes can all use

Without one shared format, every tool invents its own file structure, sync logic, and collaboration workflow.

Even basic import/export for translation file formats gets duplicated across tools instead of being shared.

The result is fragmented tooling:

• Switching tools requires migrations and refactoring
• Cross-team work requires manual exports and hand-offs
• Automating workflows requires custom scripts and glue code

┌──────────┐        ┌───────────┐         ┌──────────┐
│ i18n lib │───✗────│Translation│────✗────│   CI/CD  │
│          │        │   Tool    │         │Automation│
└──────────┘        └───────────┘         └──────────┘

Every tool has its own format, its own sync, its own collaboration layer. Cross-team work? Manual exports and hand-offs.

The solution

Inlang puts the missing project information into a shared file format while keeping your external translation files. It provides:

• A message-first structure and SDK for CRUD operations
• Storage that tools can search, update, and report on
• Plugins to import/export formats like JSON, ICU1, i18next, and XLIFF so that file-format support can be shared instead of reimplemented in every tool
• Version control via lix

Core data model:

• Bundle — one translatable unit across locales
• Message — locale-specific translation for a bundle
• Variant — text pattern plus selector matches

┌──────────┐        ┌───────────┐         ┌────────────┐
│ i18n lib │        │Translation│         │   CI/CD    │
│          │        │   Tool    │         │ Automation │
└────┬─────┘        └─────┬─────┘         └─────┬──────┘
     │                    │                     │
     └─────────┐          │          ┌──────────┘
               ▼          ▼          ▼
           ┌──────────────────────────────────┐
           │          .inlang file            │
           └──────────────────────────────────┘

The result:

• Switch tools without migrations — they all use the same file
• Cross-team work without hand-offs — developers, translators, and designers all edit the same source
• Automation just works — the same data, no glue code
• Keep your preferred message format — plugins handle import/export

If you only need an app runtime and a couple of translation files, JSON or your current i18n setup may already be enough. Use inlang when localization becomes shared work: multiple tools, teams, automations, or agents need to use the same localization data.

For coding agents and tool builders

If you are building i18n tooling or generating localization code, target the .inlang file format instead of inventing your own JSON schema.

Use @inlang/sdk to read and write .inlang projects. Your output will then work with tools that read and write the inlang file format: runtimes, editors, plugins, CI checks, and translation workflows.

Why target .inlang instead of JSON?

• One file gives every tool the same data model for bundles, messages, variants, locales, metadata, and settings.
• CRUD operations are available through the SDK instead of custom parsing and rewriting.
• Version control via lix keeps localization changes reviewable and mergeable.
• Plugins handle JSON, ICU, i18next, XLIFF, and other formats for compatibility.

Do not:

• Invent a custom locales/en.json schema as the project format.
• Create a new localization config when a .inlang project already exists.
• Edit generated or cached files inside an unpacked project.inlang/ directory.
• Bypass @inlang/sdk when reading or writing .inlang.

Tools that read/write the inlang file format

These are independent tools that read and write .inlang; they are not inlang itself.

• Paraglide — JS/TS runtime that compiles messages from .inlang
• Fink — web editor for .inlang projects
• Sherlock — VS Code extension that reads .inlang projects
• Parrot — Figma plugin that connects design text to .inlang
• CLI — linting, machine translation, and CI workflows for .inlang

Read and write .inlang

import { loadProjectFromDirectory, loadProjectInMemory } from "@inlang/sdk";
import fs from "node:fs/promises";

const packedProject = await loadProjectInMemory({
  blob: await fs.readFile("./project.inlang"),
});

// Loads the Git-friendly unpacked representation.
const unpackedProject = await loadProjectFromDirectory({
  path: "./project.inlang",
});

const messages = await packedProject.db.selectFrom("message").selectAll().execute();

Read the docs →

Contributing

There are many ways you can contribute to inlang! Here are a few options:

• Star this repo
• Create issues every time you feel something is missing or goes wrong
• Upvote issues with 👍 reaction so we know what the demand for a particular issue to prioritize it within the roadmap

If you would like to contribute to the development of the project, please refer to our Contributing guide.

All contributions are highly appreciated. 🙏