Developing a URL Shortening Service (TinyURL)

A URL shortening service takes long URLs, making them shorter and easier to handle. When clicked, these shortened URLs forward users to their longer counterparts.

This Cloud Lab focuses on developing a highly available, scalable, and resilient URL shortening service using AWS. The initial step involves setting up a DynamoDB table and DAX cluster for caching and storing key pairs of long URLs and their short URL equivalents. You’ll then create a Flask application within your EC2 instance. Next, you’ll configure an Auto Scaling group to manage your EC2 instances. Lastly, you’ll use an Application Load Balancer to manage incoming traffic and implement rate limiting with WAF. 

After completing this Cloud Lab, you can deploy a fully functional, end-to-end URL shortening service, leveraging the power and scalability of AWS cloud services. The provisioned infrastructure is provided in the architecture diagram below for reference.

Why URL shorteners are a classic system design problem

URL shortening services look simple on the surface: take a long URL and return a short one. However, behind that simplicity lie numerous real-world backend challenges, including high read traffic, low latency, data durability, and reliability.

That’s why URL shorteners are a common teaching example. They condense several key system design ideas into a problem that’s easy to understand and extend.

The core components of a URL shortening system

Most URL shorteners include the same fundamental pieces:

• API layer: An API receives requests to create short URLs and handles redirects when users access them.

• ID generation: The system requires a reliable method to generate short, unique identifiers that won’t collide as usage increases.

• Storage: Short URLs must be mapped to long URLs in a durable data store capable of handling high read traffic.

• Redirection logic: When a user accesses a short URL, the system must resolve it quickly and redirect with minimal latency.

• Scalability and availability: Because read traffic is typically much higher than write traffic, caching and horizontal scaling are critical.

Common design decisions and trade-offs

Building a URL shortener forces you to think about trade-offs:

• ID strategy: Random strings vs. sequential IDs vs. hash-based approaches.

• Storage choice: Key-value stores vs. relational databases.

• Caching: Reducing database reads for popular links.

• Expiration policies: Temporary vs. permanent links.

• Analytics: Tracking clicks without slowing redirects.

There’s no single “right” design; the best choice depends on scale, traffic patterns, and reliability requirements.

How cloud platforms simplify the design

Cloud services reduce operational overhead by providing managed building blocks:

• Managed databases for durable storage.

• Serverless compute or containers for API logic.

• Load balancers and routing for traffic management.

• Monitoring and logging for visibility into usage and failures.

The important lesson isn’t which service you choose, it’s how the pieces fit together.

Why this pattern generalizes beyond URL shortening

Once you understand how a URL shortener works, the same ideas apply to:

• Session management systems

• Feature flag services

• Referral and tracking links

• Key-based lookup APIs

• High-read, low-write backend services

It’s a small system with outsized learning value.