Requirements

Functional Requirements:

• Create a short URL for a given long URL.
• Return the long URL associated with a given short URL.

Non-Functional Requirements:

• List the key non-functional requirements (eg low latency, scalability, reliability, etc.)...

1. High Availability (Major) — If the service goes down, millions of links break. Users can't access their saved URLs. The system must stay up even if servers fail.

2. Low Redirect Latency (Major) — When someone clicks a short URL, the redirect should happen in milliseconds. Nobody waits for a redirect.

3. Horizontal Scalability (Minor) — The system should handle traffic spikes (viral links) by adding more servers, not upgrading one machine.

4. Durability — Shortened URLs should never be lost once created. Data persistence is critical.

API Design

Define the APIs expected from the system. This is your chance to analyze and define the read and write paths so that you can come up with the high-level design...

1. Create Short URL

Request : POST /shorten

{

"long-url" : "https://www.example.com/test/",

"alias" : "my-link"

}

Response:

{

"short_url":"https://short.com/157147",

"long_url":"https://www.example.com/test/",

"code":"157147",

"created_at" : "2026-06-12 10:34:34"

}

2.Redirect Url

GET /{short_code}

Response: 301 Redirect to the original long URL (or 302 if you want to track click analytics).

GET /{short_code}/stats

Response:

{ "short_code": "abc123", "total_clicks": 452, "created_at": "2024-01-15T10:30:00Z"}

• Use 301 (permanent) if you want browsers to cache the redirect for performance
• Use 302 (temporary) if you want to track every click via analytics
• Adding custom_alias support is a great differentiator in interviews

High-Level Design

Describe the overall system architecture. Identify the main components needed to solve the problem end-to-end. Use the diagramming tool to create a block diagram.

Detailed Component Design

Deep dive into 2-3 key components. Explain how they work, how they scale, discuss tradeoffs, capacity, and any relevant algorithms or data structures.