URL Shortener Service

A production-ready URL shortening service built with Spring Boot (Kotlin) that converts long URLs into short, shareable links.

Features

• URL Shortening: Convert long URLs to short url
• Redirection: 301 redirects from short URLs to original destinations
• Metadata Lookup: get original URL without redirection
• Duplicate Handling: Returns existing short URL if URL was previously shortened
• Race Condition Protection: Handles concurrent requests gracefully
• Distributed ID Generation: Uses Sonyflake for unique ID generation
• Base62 Encoding: Generates compact, human-friendly short codes
• Caching: Improves performance for frequently accessed URLs

Tech Stack

• Backend: Spring Boot (Kotlin)
• Database: JPA/Hibernate (mysql used)
• Cache: Spring Cache abstraction
• ID Generation: Sonyflake
• Encoding: Base62 for short code generation
• UrlValidation: Apache Commons Validator
• API Docs: OpenAPI(Swagger)

API Endpoints

URL Shortener Service

API Endpoints

Shorten URL

POST /api/v1/urls
Content-Type: application/json

{
  "longUrl": "https://example.com/very/long/url"
}
Response:

json
{
  "shortKey": "abc123",
  "shortUrl": "https://domain/abc123"
}

Redirect to Original URL

http
GET /{shortKey}
Returns 301 redirect to original URL

Get URL Metadata

GET /{shortKey}/meta
Response:

json
{
"originalUrl": "https://example.com/very/long/url"
}

Getting Started

• install docker
• navigate to project root then run: docker compose up --build

Access Swagger UI:

• navigate to: http://localhost:8080/swagger-ui.html

To run the project locally:

• connect to MYSQL database and update DB connection in application properties
• this project uses java 17, make sure it's installed
• run :

./gradlew bootRun

Run tests:

./gradlew test

Configure base domain:

• to configure the short url domain, go to application.properties and change:

app.domain= <Your Domain>

Phase2 and improvements:

• add Redis to cache frequently requested Urls
• Rate Limiting