The classic Gang of Four book that introduced design patterns to software engineering. This foundational text catalogs 23 essential design patterns that have become the standard vocabulary for object-oriented design. Essential reading for any serious software engineer.

The foundational text that introduced design patterns to software engineering. This book, written by the Gang of Four (Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides), catalogs 23 essential design patterns that have become the standard vocabulary for object-oriented design. While the examples are in Smalltalk and C++, the patterns themselves are language-agnostic and apply to modern languages like Java, Python, JavaScript, and more. The book is organized into three categories: creational patterns (like Factory and Singleton), structural patterns (like Adapter and Decorator), and behavioral patterns (like Observer and Strategy). Each pattern includes a detailed explanation, motivation, structure, participants, collaborations, consequences, implementation, sample code, known uses, and related patterns. This book is essential reading for any serious software engineer who wants to understand how to design flexible, reusable, and maintainable software.

The classic Gang of Four book that introduced design patterns to software engineering. Catalogs 23 essential patterns for flexible object-oriented design.

Design Patterns: Reusable Object-Oriented Software Guide

Design Patterns: Elements of Reusable Object-Oriented Software

Any fool can write code that a computer can understand. Good programmers write code that humans can understand.

Fowler and Beck’s second edition of Refactoring is still the book I hand to engineers when we’re about to touch legacy code. The catalog of refactorings—Extract Function, Introduce Parameter Object, Replace Conditional with Polymorphism—gives you named moves with mechanics, motivations, and before/after examples you can translate to any language. Over the last year we’ve used it to modernize a decade-old Java service and a pile of TypeScript reducers; the step-by-step recipes paired with tests kept us shipping safely instead of rewriting from scratch. The newer chapters address lambdas, streams, and microservices, and the online catalog makes it easy to search for a particular smell mid-PR. If you refactor as part of your day job (and you should), this belongs on your desk.

Martin Fowler's systematic guide to refactoring code. Learn named refactoring moves with step-by-step mechanics to improve code design safely and effectively.

Refactoring: Improving the Design of Existing Code

Refactoring: Improving the Design of Existing Code (2nd Edition)

Curated design patterns products we use and recommend. Each item tested in real-world scenarios. Find 2 products with detailed reviews, pros, and cons.

Design Patterns Products

Design Patterns: Elements of Reusable Object-Oriented Software

Refactoring: Improving the Design of Existing Code (2nd Edition)