Design a URL shortening platform that maps long URLs to short codes and supports redirection at scale. Define the API (create, expand, delete), code generation strategy (hashing, base-N encoding, collision handling), custom aliases, and TTL/expiration. Propose a data model and storage choices for billions of links, and a read-heavy architecture with caches and CDN. Describe rate limiting, abuse/fraud prevention, analytics (click counts, uniques, geo, time), and GDPR/compliance considerations. Provide a capacity plan (QPS, storage), a fault-tolerant deployment (replication, sharding), and consistency trade-offs.

This question evaluates competency in system design and distributed systems architecture, including API design, scalable short-code generation, data modeling and storage/sharding, caching and CDN strategies, consistency and fault-tolerance trade-offs, rate limiting and abuse prevention, analytics, compliance, and capacity planning.

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Design a URL shortening platform | Amazon Interview Question

Design a Scalable URL Shortening Platform

Context

Build a Bitly-like URL shortener that maps long URLs to short codes and performs HTTP redirection reliably at global scale. Assume the service is read-heavy, stores billions of links, and must meet low latency and high availability requirements.

Requirements

APIs

Define REST APIs for:
- Create short link (with optional custom alias and TTL)
- Expand short code to original URL (preview)
- Delete/disable a short link

Short Code Generation

Strategy: hashing and/or counter-based IDs
Base-N encoding (e.g., base62)
Collision handling
Support custom aliases
TTL/expiration behavior

Data Model and Storage

Schema for links, users, and analytics
Storage for billions of links (trade-offs: SQL vs NoSQL, KV stores)
Indexing and sharding strategy

Read-Heavy Architecture

Caches (edge and regional)
CDN and edge compute considerations
Redirect behavior (301/302/307) and caching semantics

Rate Limiting and Abuse Prevention

Per-IP/account rate limiting
Malware/phishing detection, Safe Browsing integration
Blacklist/allowlist, link scanning

Analytics

Click counts, uniques, geo, time-of-day
Real-time vs batch pipelines

GDPR/Compliance

Data minimization, retention, encryption
Right-to-be-forgotten, data residency

Capacity Plan

QPS estimates (create vs redirect)
Storage sizing (links and logs)

Fault-Tolerant Deployment

Multi-AZ/region replication
Sharding, failover

Consistency Trade-offs

Strong vs eventual consistency (creation, expansion, deletion)
Global uniqueness of custom aliases

Design a Scalable URL Shortening Platform

Context

Requirements

APIs

Define REST APIs for:
- Create short link (with optional custom alias and TTL)
- Expand short code to original URL (preview)
- Delete/disable a short link

Short Code Generation

Strategy: hashing and/or counter-based IDs
Base-N encoding (e.g., base62)
Collision handling
Support custom aliases
TTL/expiration behavior

Data Model and Storage

Schema for links, users, and analytics
Storage for billions of links (trade-offs: SQL vs NoSQL, KV stores)
Indexing and sharding strategy

Read-Heavy Architecture

Caches (edge and regional)
CDN and edge compute considerations
Redirect behavior (301/302/307) and caching semantics

Rate Limiting and Abuse Prevention

Per-IP/account rate limiting
Malware/phishing detection, Safe Browsing integration
Blacklist/allowlist, link scanning

Analytics

Click counts, uniques, geo, time-of-day
Real-time vs batch pipelines

GDPR/Compliance

Data minimization, retention, encryption
Right-to-be-forgotten, data residency

Capacity Plan

QPS estimates (create vs redirect)
Storage sizing (links and logs)

Fault-Tolerant Deployment

Multi-AZ/region replication
Sharding, failover

Consistency Trade-offs

Strong vs eventual consistency (creation, expansion, deletion)
Global uniqueness of custom aliases

Design a URL shortening platform

Quick Overview

Design a Scalable URL Shortening Platform

Context

Requirements

Solution

Comments (0)

Design a URL shortening platform

Quick Overview

Design a Scalable URL Shortening Platform

Context

Requirements

Solution

Comments (0)