exp-gen 🚀

exp-gen a lightning-fast, interactive CLI tool designed to scaffold Express.js REST APIs in seconds.

Whether you're starting a project with TypeScript or JavaScript, exp-gen generates a clean layered architecture, configures your preferred database boilerplate so you can start coding immediately, and now includes a built-in web-based Regex Simulator to help you build and debug regular expressions visually.

✨ Features

• 🚀 Interactive CLI powered by @clack/prompts
• ⚡ Scaffold Express.js APIs in seconds
• 🟦 TypeScript support
• 🟨 JavaScript support
• 🗂 Professional layered architecture
• 🍃 MongoDB (Mongoose)
• 🐬 MySQL
• 🪶 SQLite
• 🐘 PostgreSQL (JavaScript projects)
• 📦 Optional automatic dependency installation
• 🔬 Built-in Regex Simulator
• 🌐 Opens automatically in your browser
• 🎨 Modern developer-friendly UI
• 📖 Live regex explanation & validation

🚀 Installation

Install globally using npm:

npm install -g @madhusha_99/exp-gen

🚀 Usage

After installation you can launch the CLI using any of the following commands:

exp

or

gen

or

express-draft

When the CLI starts you'll be greeted with an interactive menu.

🚀 Scaffold a new Express API

🔬 Run Regex Simulator

🚀 Scaffold Express API

Choose Scaffold a new Express API and answer a few questions.

The CLI will ask for:

• Project name
• Language
• Database
• Install dependencies

Supported languages

• TypeScript (Recommended for type safety) – Currently available with MongoDB (Mongoose) and No Database templates. More database integrations will be added in future releases.
• JavaScript – Full template support for all currently available databases, including MongoDB (Mongoose), MySQL (mysql2), SQLite (sqlite3), PostgreSQL (pg), and No Database.

🗄️ Supported Databases

| Database | JavaScript | TypeScript | Driver / ORM | Status | | ------------------- | :--------: | :--------: | ------------ | :-----: | | MongoDB | ✅ | ✅ | Mongoose | Stable | | MySQL | ✅ | ❌ | mysql2 | Stable | | SQLite | ✅ | ❌ | sqlite3 | Stable | | PostgreSQL | ✅ | ❌ | pg | Stable | | None (No Database) | ✅ | ✅ | — | Stable | | Prisma (MongoDB) | 🚧 | 🚧 | Prisma ORM | Planned | | Prisma (MySQL) | 🚧 | 🚧 | Prisma ORM | Planned | | Prisma (PostgreSQL) | 🚧 | 🚧 | Prisma ORM | Planned | | Prisma (SQLite) | 🚧 | 🚧 | Prisma ORM | Planned |

Preview

📁 Project Structure

• configs/: Environment variables and database connection logic.
• controllers/: Bridges the routes and the business logic; handles requests/responses.
• dtos/: Data Transfer Objects for validating and shaping incoming data.
• interfaces/: TypeScript interfaces and types for strict type safety.
• middlewares/: Custom Express middlewares (Auth, Error handling, Logging).
• models/: Database schemas (e.g., Mongoose/MongoDB models).
• repositories/: The data access layer; handles direct database operations.
• routes/: API endpoint definitions and mapping to controllers.
• services/: Core Business Logic layer; where the heavy lifting happens.
• utils/: Shared helper functions and utility classes.
• app.ts: The application entry point.

The generated architecture follows a clean layered design making projects easier to maintain and scale.

🔬 Regex Simulator

Starting from v1.4.0, exp-gen includes a fully interactive Regex Simulator.

Simply choose:

🔬 Run Regex Simulator

The CLI automatically starts a lightweight local server and opens the Regex Simulator in your default web browser.

✅ No additional dependencies are required. The simulator is built into exp-gen and runs entirely on your local machine.

Preview

Features in Regex Simulator

• ⚡ Live regex matching
• 📖 Regex rule explanations
• 🎯 Capture group visualization
• 🔍 Match position detection
• 🚨 Friendly validation errors
• 🧠 Beginner-friendly regex guidance
• 🏷 Regex flag helper
• 🌙 Modern dark developer UI
• 🌐 Runs completely locally

Example

(?<name>\w+)-(\d+)

Input:

hello-123
world-456
invalid-value

Output:

✓ Match 1
hello-123

Group 1:
hello

Group 2:
123

The simulator also explains regex tokens such as:

| Token | Description | | ----------- | ------------------- | | \d | Digit | | \w | Word character | | . | Any character | | + | One or more | | * | Zero or more | | ? | Optional | | ^ | Start of input | | $ | End of input | | () | Capture group | | (?<name>) | Named capture group |

🚀 Example Workflow

exp

✔ What would you like to do?

❯ 🚀 Scaffold a new Express API
  🔬 Run Regex Simulator

or

✔ What would you like to do?

  🚀 Scaffold a new Express API
❯ 🔬 Run Regex Simulator

📦 After Scaffolding

Navigate into your project

cd my-project

If dependencies were installed

npm run dev

Otherwise

npm install
npm run dev

🤝 Contributing

We love open source! exp-gen is a community-driven project, and we welcome contributions to make it better.

You can help by:

• Adding new database templates
• Improving generated project templates
• Improving the Regex Simulator
• Reporting bugs
• Suggesting new CLI features

Clone the project

git clone https://github.com/Open-Core-Lab/exp-gen.git

Install dependencies

npm install

Run locally

npm run dev

📋 Roadmap

Upcoming features include:

• Prisma support
• Docker template generation
• JWT Authentication template
• Swagger/OpenAPI generation
• Testing templates (Vitest/Jest)
• Redis integration
• Prisma PostgreSQL template
• Environment profile generator
• More Regex Simulator utilities

⭐ Support

If you enjoy using exp-gen, consider giving the repository a ⭐ on GitHub.

It helps the project grow and supports future development.

Repository: exp-gen

📄 License

This project is licensed under the MIT License.

Happy coding! 🚀

Maintained with ❤️ by Madhusha Prasad