URL Shortener

A URL shortening service built with Express and Neon Postgres, deployable on Vercel. Takes long URLs and generates short, shareable codes using a base62 encoding scheme.

Live demo: https://code-alpha-url-shortner.vercel.app/

Features

• Shorten any valid URL into a 7-character code
• Duplicate detection — the same long URL always returns the same short code
• Redirect via the short code to the original URL
• Admin page at /admin to view all stored URLs or reset the database
• Data persists across deployments via Neon Postgres
• URL validation via the validator library (requires http/https protocol and a valid domain, IP, or localhost)
• Rate limiting on /shorten (max 10 requests per 15 minutes per IP) to prevent abuse
• Random-looking short codes generated via a bijective LCG permutation (no sequential guessing, zero DB collision checks)

Prerequisites

• Node.js 18+
• A Neon Postgres database (serverless Postgres). You can create one through the Vercel Storage tab or directly at neon.tech.

Installation

1. Clone the repo and install dependencies:

git clone https://github.com/HelmyIsMad/CodeAlpha_URLShortner.git
cd CodeAlpha_URLShortner
npm install

2. Set up your Neon Postgres database and get the connection string. It looks like:

postgresql://user:password@ep-xxx.us-east-2.aws.neon.tech/neondb?sslmode=require

3. Create a .env file in the project root with your connection string:

DATABASE_URL=postgresql://user:password@ep-xxx.us-east-2.aws.neon.tech/neondb?sslmode=require

4. Start the server:

npm start

The app runs at http://localhost:3000.

Usage

Endpoint	Description
GET /	Main page with a URL shortening form
POST /shorten	API to shorten a URL (JSON body: { "longUrl": "..." }). Rate-limited to 10 req/15min per IP. Returns 400 for invalid URLs, 429 when rate-limited
GET /:code	Redirects a short code to the original URL
GET /admin	Admin panel to view/reset the database

Deployment (Vercel)

Push the repo to GitHub and import it into Vercel. Add a Neon Postgres database via the Vercel Storage tab — the DATABASE_URL environment variable is injected automatically. No manual .env setup needed on Vercel.

Project Structure

├── api/
│   └── index.js           — Vercel serverless entry point
├── src/
│   ├── server.js          — Server entry point (starts listener)
│   ├── app.js             — Express app setup (middleware, routes, rate limiter)
│   ├── routes/index.js    — Route definitions
│   ├── controllers/urlController.js — Request handlers
│   ├── config/database.js — Database layer (Neon Postgres)
│   └── utils/helpers.js   — Base62 encoder, URL validator, baseURL helper
├── templates/
│   ├── index.html         — Homepage with URL shortening form
│   └── admin.html         — Admin panel
├── vercel.json            — Vercel deployment config
├── .env                   — Local environment variables (not tracked)
└── .env.example           — Example environment variables