Auth0 International Email Generator: CLI for Multilingual Templates

Auth0 Email Internationalization: The Challenge of Multilingual Templates

Auth0 multilingual email management and authentication template internationalization represent a major challenge for developers. Between email translation, HTML template validation, language fallback management, and integration across different environments, i18n projects quickly become complex.

To solve these Auth0 internationalization challenges, I developed the Auth0 International Email Generator¹. This TypeScript CLI tool automates multilingual email template generation with integrated validation, fallback systems, and complete configuration for international authentication.

How does it work?

Quick installation and setup

# Clone the repo
git clone https://github.com/Lingelo/auth0-international-email.git
cd auth0-international-email

# Install dependencies
yarn install

# Interactive project setup
yarn init

Multilingual Configuration and i18n Internationalization

The internationalized configuration in config.json handles all aspects of i18n for Auth0:

{
  "supportedLanguages": ["en", "fr", "es", "de", "pt"],
  "defaultLanguage": "en",
  "fallbackStrategy": "cascade",
  "templates": {
    "welcome_email": {
      "fromAddress": "hello@myapp.com",
      "subjectKey": "welcome.subject",
      "i18nEnabled": true
    },
    "password_reset": {
      "fromAddress": "security@myapp.com",
      "subjectKey": "password.reset.subject"
    }
  }
}

If an Auth0 email translation is missing, the intelligent language fallback system automatically switches to the default language. No more broken authentication emails in production!

Automatic generation and validation

Secure Liquid Templates for Internationalization

The Auth0 template generator uses Liquid (Shopify’s template engine) to create secure internationalized emails. This approach avoids vulnerabilities like eval():

<h1></h1>
<p></p>
<p></p>
<footer></footer>

Each multilingual email template benefits from automatic internationalization with user variable management.

Triple validation

Before generating, the tool checks:

Valid HTML: Correct structure, no broken tags
Correct Liquid: Syntax and variables OK
Complete translations: All keys exist in every language

# Validate entire project
yarn validate

# Generate final templates
yarn generate

Interactive CLI and developer experience

Modern interface with Inquirer

The tool asks the right questions and generates the config automatically:

? Which languages to support? (en, fr, es)
? Welcome email? (welcome_email) 
? Sender address? noreply@myapp.com
? Base template? Select a template...

Complete dev integration

ESLint + Prettier: Automatic clean code
Jest: Unit tests for validation
TypeScript: Strict typing, no runtime errors
Fast build: 4 parallel workers

# Complete dev workflow
yarn lint     # Check code
yarn test     # Run tests  
yarn build    # Compile everything

Generated template structure

File organization

After generation, you get this in dist/output/:

dist/output/
├── welcome_email_en.html
├── welcome_email_fr.html  
├── welcome_email_es.html
├── password_reset_en.html
├── password_reset_fr.html
└── translations/
    ├── en.json
    ├── fr.json
    └── es.json

Templates ready for Auth0

Each template is directly usable in Auth0:

<!-- welcome_email_fr.html -->
<!DOCTYPE html>
<html lang="fr">
<head>
  <meta charset="UTF-8">
  <title>Welcome !</title>
</head>
<body>
  <h1>Hi  👋</h1>
  <p>Your account is created, you can log in!</p>
</body>
</html>

Plugins and extensibility

Modular plugin system

You can easily extend functionality:

// config.json
"plugins": [
  "html-validator",    // Validate HTML
  "minifier",          // Minify code  
  "asset-optimizer",   // Optimize images
  "analytics-tracker"  // Track usage
]

CI/CD integration

Perfect for GitHub Actions or GitLab CI:

# .github/workflows/emails.yml
- name: Generate templates
  run: |
    yarn install
    yarn validate
    yarn generate
    
- name: Upload to Auth0
  run: |
    # Script to upload templates
    ./deploy-to-auth0.sh

Real-world use cases

Complete multilingual app

Say you have an app with French, English and Spanish users:

Initial setup: yarn init and configure your 3 languages
Translations: Fill JSON files in translations/
Templates: Create your Liquid templates in templates/
Generation: yarn generate produces all emails
Auth0 upload: Copy-paste into your Auth0 dashboard

Team workflow

# Backend dev sets up project
yarn init

# Designer creates HTML templates
vim templates/welcome_email.liquid

# Translator fills JSON files
vim translations/fr.json

# Generate and test
yarn generate
yarn test

# Deploy to prod
git commit -am "feat: new multilingual emails"

Why use this?

Huge time savings

No more manual copy-pasting of emails into Auth0. No more forgotten translations. No more broken emails in prod.

Before: 2-3 hours to add a language
After: 10 minutes to generate all templates

Maintainable code

Version control: Your emails are in Git, not lost in the Auth0 interface
Review process: Changes go through PRs like the rest of your code
Automatic tests: Impossible to deploy broken templates
Complete history: You see who changed what and when

Organized team

Role separation: Dev = structure, Designer = HTML, Translator = content
Automatic validation: No need to check manually
Live documentation: The config explains everything

Conclusion: Master Your Auth0 Email Internationalization

The Auth0 International Email Generator revolutionizes multilingual authentication email management. This TypeScript + CLI + Liquid solution dramatically simplifies Auth0 template internationalization while ensuring security and maintainability.

For teams facing Auth0 i18n challenges, this internationalization tool offers:

Automatic generation of multilingual templates
Integrated validation of translations and syntax
CI/CD integration for professional workflows
Intelligent language fallback to prevent errors

Investment: 10 minutes setup
Return: Hours saved on every new template or added language

An essential solution for any project requiring robust international authentication.

Sources

Auth0 International Email Generator - GitHub Repository - Angelo Lima
Auth0 Email Templates Documentation - Auth0 Official Documentation
Liquid Template Language Documentation - Shopify
TypeScript Project Configuration Best Practices - TypeScript Team
Node.js CLI Best Practices - Liran Tal

Tags: Développement Web Sécurité Auth0 TypeScript i18n