Simple Localize

A simple and efficient Python module to easily add localization (multilingual support) to your projects.

Installation

pip install simple-localize

Quick Start

import simple_localize

simple_localize.init_localizer('your_translations.json')
print(simple_localize.get_text('your_text_key'))  # Auto-detects your language

Features

• 🌍 Auto-detects your system language
• 📁 JSON-based translations (easy to edit)
• 🔄 Switch languages on the fly (per-thread safe)
• 🎯 Text formatting with variables
• ⚠️ Missing key warnings with helpful suggestions
• ⚡ Zero dependencies - uses only Python standard library
• 🔒 Thread-safe - safe to use in multi-threaded apps (Flask, FastAPI…)

Basic Examples

# Get text in your system language
message = simple_localize.get_text('welcome_message')

# Get text in specific language
french_msg = simple_localize.get_text('welcome_message', 'fr')

# Change current language
simple_localize.set_language('es')

# Use variables in text
greeting = simple_localize.get_text('greeting', name="Alice")

API Reference

Create Your Translation File

Create a JSON file with any name you like (my_texts.json, lang.json, app_translations.json, etc.):

{
  "app_title": {
    "en": "My Application",
    "fr": "Mon Application",
    "es": "Mi Aplicación"
  },
  "login_button": {
    "en": "Login",
    "fr": "Connexion",
    "es": "Iniciar sesión"
  },
  "welcome_user": {
    "en": "Welcome {username}!",
    "fr": "Bienvenue {username} !",
    "es": "¡Bienvenido {username}!"
  }
}

Then use it in your code:

import simple_localize

simple_localize.init_localizer('my_app_texts.json')
print(simple_localize.get_text('app_title'))
print(simple_localize.get_text('welcome_user', username="John"))

Thread Safety

set_language() applies per thread — each thread can have its own active language without affecting others. This makes it safe to use in web servers where each request runs in its own thread:

# Thread A (e.g. a French user's request)
simple_localize.set_language('fr')
simple_localize.get_text('welcome')  # → French
simple_localize.get_text('goodbye')  # → French too

# Thread B (e.g. a Spanish user's request), simultaneously
simple_localize.set_language('es')
simple_localize.get_text('welcome')  # → Spanish, unaffected by Thread A

add_translations() is also thread-safe for concurrent writes.

Supported Languages

Add any languages you need! Use standard ISO 639-1 codes (en, fr, pt…) or regional variants (pt_br, pt_pt, en_us…).

The fallback chain for a pt_br user:

1. pt_br — exact match
2. pt — language fallback
3. default language (usually en)

{
  "hello": {
    "pt_br": "Olá (Brasil)",
    "pt_pt": "Olá (Portugal)",
    "pt": "Olá",
    "en": "Hello"
  }
}