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The original QTranslate by Questsoft was the best desktop translation tool on Windows — until development stopped, APIs broke, and users were left with a dead app.

This is a full rewrite in Kotlin with one core design change: everything is a plugin. Translation engines, OCR, TTS, spell checkers, dictionaries — all separate JARs you install at runtime. When a service changes its API or shuts down, you swap the plugin. The app keeps running.

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What it does

Select text anywhere → press Ctrl+Q → translation appears instantly. That's the core of it.

For longer work: open the main window, type or paste, translate. Switch engines in one click. Run OCR on a screenshot. Listen to pronunciation. Check spelling. Browse history. All from the keyboard, all without opening a browser.

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Features

Translation

Quick Translate popup	Ctrl+Q on any selected text — popup with result, no main window needed
Instant translation	Translates as you type with configurable debounce
Inline replace	Ctrl+Shift+T — translates selected text and pastes the result back in place
Backward translation	See the round-trip result alongside the main output — spots awkward phrasing instantly
Summarize	Get a condensed version of long text, configurable length
Rewrite	Rewrite in a different style: Formal, Casual, Concise, Detailed, or Simplified
Translation history	Full undo/redo through every past translation
Translation rules	Auto-correct source text before translating — fix common mistakes, expand abbreviations, normalize input

Input

Screen OCR	Draw a rectangle anywhere on screen — translate, copy text, copy image, or save; re-crop without closing
Spell checking	Live underlines as you type, click a suggestion to apply
Remove line breaks	Strips newlines from pasted text so PDF content translates as sentences
Language filter	Pin 3–4 target languages so the picker isn't overwhelming
Cycle languages	Ctrl+L steps through pinned languages without touching the mouse

Services & plugins

Plugin system	Install .jar plugins at runtime — no restart, no reinstall
Service presets	Save different engine combinations for different contexts
Google Services	Translator, TTS, OCR, Spell Checker, Dictionary — included
Bing Services	Translator, TTS, Spell Checker — included
AI Services	Translator, Summarizer, Rewriter, Spell Checker, Dictionary, Vision OCR — via OpenRouter (300+ models, one API key) — included

Interface

Three layouts	Classic (stacked), Side-by-side, Compact (tabbed)
Global hotkeys	Every action is bindable, configurable as global or app-local
RTL support	Full layout mirroring for Arabic, Hebrew, Farsi, and more
30+ themes	Dark and light via FlatLaf, with animated transitions — drop any IntelliJ .theme.json into the themes/ folder to add more
Portable	Runs from any folder, all data lives next to the JAR

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Installation

Requires Java 11 or later — download from Adoptium if you need it.

1. Download QTranslate-<version>.zip from Releases
2. Unzip anywhere
3. Run QTranslate.jar

QTranslate/
  ├── QTranslate.jar                  ← double-click, or: java -jar QTranslate.jar
  ├── plugins/
  │     ├── google-services-plugin.jar
  │     ├── bing-services-plugin.jar
  │     └── ai-services-plugin.jar
  ├── themes/
  │     └── kokedera.theme.json       ← community theme included; drop more .theme.json files here
  └── languages/
        ├── ar-SA.toml
        ├── zh-CN.toml
        ├── de-DE.toml
        └── ...

Google, Bing, and AI plugins are included. Add your API keys in Settings → Plugins → [plugin] → Configure.

Getting "This application requires a Java Runtime Environment"? Java isn't installed or JAVA_HOME isn't set. This video covers the full process: ▶ How to Install Java JDK and Set JAVA_HOME (first 7 minutes)

Build from source → Building from Source

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Quick start

1. Launch QTranslate.jar — it starts in the system tray
2. Select text anywhere on screen
3. Press Ctrl+Q — Quick Translate popup opens with the result ready
4. Press Ctrl+D — open the Dictionary for the selected word
5. Press Ctrl+E — listen to the selected text
6. Press Ctrl+I — draw a screen region to OCR and translate

Open Settings (gear icon) to configure API keys, themes, hotkeys, and service presets.

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Plugins

Installing a plugin: Settings → Plugins → Install Plugin → select .jar → Enable → Configure → assign in Services & Presets

Full guide → Installing Plugins

Community plugins

Built a plugin? Publish it on GitHub with the qtranslate-plugin topic and a qtranslate-plugin.json in your repo — it will appear automatically in QTranslate's built-in marketplace. → Plugin publishing guide

Plugin	Services	Author
(be the first — it's 50 lines of Kotlin)

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Build a plugin

A minimal translator is ~50 lines of Kotlin. No framework, no registration — implement a few interfaces, build a fat JAR, install it through the UI.

class MyPlugin : Plugin<PluginSettings.None> {
    override val id      = "com.example.my-plugin"
    override val name    = "My Plugin"
    override val version = "1.0.0"

    override fun getSettings() = PluginSettings.None
    override fun getServices() = listOf(MyTranslatorService())
}

The bundled Google, Bing, and AI plugins are fully open source in plugins/ — they're the best real-world reference for auth, language mapping, error handling, and settings.

Full guide → Creating a Plugin

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Translate the interface

QTranslate ships with 13 languages built in:

Arabic · Bengali · Chinese · English · French · German · Hungarian · Italian · Japanese · Portuguese · Russian · Spanish · Turkish

Want another language? Copy languages/en.toml, rename it to your language code, translate the values. No code needed.

Guide → Adding a Language

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Architecture

Clean Architecture + MVI. Nothing leaks between layers:

:api          ← plugin interfaces — plugins only depend on this
:core         ← business logic, use cases, MVI stores
:ui-swing     ← Swing UI, Renderable<State> components
:app          ← composition root
:plugins/*    ← Google, Bing, AI, community plugins
:plugins/common ← shared HTTP client, JSON, language utilities

Guide → Architecture

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Support

If QTranslate saves you from Alt-Tabbing to Google Translate a dozen times a day, a coffee is always appreciated!

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Contributing

Bug fixes, features, translations, docs, and plugins all welcome. Look for good first issue for well-scoped starting points.

→ Contributing Guide

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MIT License