Features

Langnostic is a modern translation toolchain that uses AI to continuously translate strings within apps and Markdown documents. It's designed for developers who want to maintain multilingual applications without the overhead of manual translation management.

AI-powered translation

Leverage the latest AI models from OpenAI, Google AI, Anthropic, and more. Langnostic uses the AI SDK by Vercel, giving you access to powerful models by these providers:

• OpenAI: GPT-5, GPT-4, GPT-4 Turbo
• Google AI: Gemini 2.5 Pro, Gemini 2.5 Flash
• Anthropic: Claude Sonnet 4.5, Claude Haiku 4.5, Claude Opus 4.1

And any provider supported by the AI SDK.

Supported file formats

Langostic's extensible system supporting multiple file formats:

• Built-in plugins for JSON and Markdown/MDX
• Flexible plugin API that allows adding support for for any file format
• Plugin-specific optimization settings

Langnostic comes with official plugins for:

JSON files

Perfect for application strings:

{
  "welcome": {
    "defaultMessage": "Welcome, {username}!",
    "description": "Greeting message for logged-in users"
  },
  "itemCount": {
    "defaultMessage": "{count, plural, =0 {no items} =1 {1 item} other {# items}}",
    "description": "Display count of items"
  }
}

Supports:

• ICU message format
• HTML/XML tags
• Template variables
• Pluralization rules

Markdown files

Ideal for documentation:

---
title: Getting Started
description: Learn how to use our platform
---

# Getting started

Welcome to our platform! Here's how to get started:

<CustomComponent prop="value" />

Supports:

• Frontmatter translation
• Markdown content translation
• JSX component preservation
• Code block preservation

Custom plugins

You can create plugins for any file format. We will create documentation for this soon.

Format preservation

Maintains the integrity of your content:

• HTML/XML tags: Preserves <div>, <span>, and other markup
• Template variables: Keeps {username}, {count} intact
• JSX components: Maintains <Component /> in MDX files
• Code blocks: Leaves code examples untranslated
• ICU message format: Supports pluralization and complex formatting

Batch processing

Efficiently processes multiple strings per request:

• Groups related translations together
• Reduces API calls and costs
• Configurable batch sizes per plugin
• Maintains context for better translation quality

Concurrent processing

Configurable parallel translation for faster results:

• Process multiple translation jobs simultaneously
• Adjustable concurrency limits
• Efficient resource utilization

Smart change detection

Only translate what's changed. Langnostic's built-in plugins intelligently tracks:

• New strings that haven't been translated
• Modified source strings that need retranslation
• Removed strings that should be cleaned up

This saves both time and API costs by avoiding unnecessary translation calls.