Open-Closed Principle

Software entities should be open for extension but closed for modification. Design modules that can be extended without modifying their source code.

4 Lessons

Knowledge Course

Open-Closed: Extend Without Modifying

Why modules should be open for extension but closed for modification.

45 min→

Open-Closed in Production: Plugins and Policies

Plugin architectures, policy extension, and keeping cores stable under feature growth.

60 min→

Advanced Open-Closed: Evolutionary APIs

APIs that evolve without breaking callers, and contracts that stay stable for decades.

75 min→

Open-Closed: Review & Mastery Quiz

Scenario questions on extension, plugins, and API evolution.

quiz30 min→

Curated Resources

Free Books & Guides

Open-Closed Principle — In-Depth Guide

A comprehensive free guide explaining the Open-Closed Principle principle with examples and best practices.

Wikipedia — Open-Closed Principle

Wikipedia article covering the Open-Closed Principle principle, its history, and applications.

Official Documentation

Wikipedia — Open-Closed Principle

The definitive reference article for Open-Closed Principle.

Martin Fowler — Open-Closed Principle

Martin Fowler's authoritative writings on software architecture and design principles.

Video Courses

Open-Closed Principle — Explained (YouTube)

A video explanation of the Open-Closed Principle principle with practical examples.

freeCodeCamp — Software Architecture Course

A comprehensive course covering software architecture principles, patterns, and best practices.

ByteByteGo — Distributed Systems

High-quality animated explanations of system design principles, distributed systems, and architecture patterns.

Practice & Examples

Awesome System Design (GitHub)

A curated list of system design resources, including principles, patterns, and interview preparation.

System Design 101 (GitHub)

Visual guides and architectural diagrams explaining key system design principles and patterns.

Reference & Cheatsheets

Martin Fowler — Software Architecture Guide

Martin Fowler's authoritative reference on software architecture principles and patterns.

Microsoft Azure Architecture Center

Microsoft's comprehensive guide to architecture principles, patterns, and best practices for cloud applications.

Articles & Blog Posts

Martin Fowler Blog

Articles and bliki entries on software architecture principles, design patterns, and best practices.

AWS Architecture Blog

Real-world architecture decisions, trade-offs, and principle applications from AWS engineers.

Community

Stack Overflow — System Design

Q&A forum for architecture, design principles, and system design questions.

Reddit r/SoftwareEngineering

Community discussions on software engineering principles, best practices, and industry trends.