KISS

Keep It Simple, Stupid

“Simplicity should be a key goal in design, and unnecessary complexity should be avoided.” – Kelly Johnson

Most systems work best if they are kept simple rather than made complicated.

When to use

Always. Every time you write code, ask: “Is there a simpler way to do this?”

Why it matters

• Maintainability: Simple code is easier to read and understand.
• Bugs: Complex code hides bugs. Simple code exposes them.
• Onboarding: New developers can understand the system faster.

Signs of Violation

• Over-engineering: Building a generic framework when a simple function would do.
• Hard-to-read code with too many abstractions.
• Solutions that require 10 files to do a “Hello World”.

Explanation

Problem

Developers often try to be “clever” or anticipate future needs that never happen, leading to complex, bloated codebases.

Solution

Write the simplest code that works for the current requirements.

Real world analogy

Tools. A hammer is a simple tool that does one thing well. A Rube Goldberg machine to crack an egg is the opposite of KISS.

Pros and Cons

Pros	Cons
Easy to read Easy to debug	Can be confused with “Quick and Dirty” (Simple code still needs to be good)

Comparison

• YAGNI: KISS implies YAGNI (don’t add complexities you don’t need).

Code example

Typescript

Bad (Violation)

Good (Adherence)

PHP

Bad (Violation)

Good (Adherence)