What Is "Dead Code"? Dead code refers to parts of a codebase that are written but never executed, called, imported, or otherwise needed during the normal operation of the application. Dead code Over time, as features are added, changed, or removed, some code becomes obsolete but is accidentally left behind. This can lead to: Increased bundle size
Slower build times
Harder maintenance and onboarding
Potential security risks Increased bundle size Increased bundle size Slower build times Slower build times Harder maintenance and onboarding Harder maintenance and onboarding Potential security risks Potential security risks Cleaning up unused code improves clarity, performance, and long-term maintainability. What Is Considered "Dead Code"? Here are the common categories of unused code: Unused Variables
Declared but never used in any operation.


Unused Functions or Methods
Defined but never called anywhere.


Unused Imports
Imported modules or packages that are never referenced.


Unused Exports
Functions or components exported from a module but not imported elsewhere.


Unused Files
Complete files (components, modules, etc.) that are never imported or required.


Unused Dependencies
Libraries listed in your package manager (e.g., package.json) that are not imported or used in the codebase. Unused Variables
Declared but never used in any operation. Unused Variables Unused Variables Declared but never used in any operation. Unused Functions or Methods
Defined but never called anywhere. Unused Functions or Methods Unused Functions or Methods Defined but never called anywhere. Unused Imports
Imported modules or packages that are never referenced. Unused Imports Unused Imports Imported modules or packages that are never referenced. Unused Exports
Functions or components exported from a module but not imported elsewhere. Unused Exports Unused Exports Functions or components exported from a module but not imported elsewhere. Unused Files
Complete files (components, modules, etc.) that are never imported or required. Unused Files Unused Files Complete files (components, modules, etc.) that are never imported or required. Unused Dependencies
Libraries listed in your package manager (e.g., package.json) that are not imported or used in the codebase. Unused Dependencies Unused Dependencies Libraries listed in your package manager (e.g., package.json) that are not imported or used in the codebase. package.json Some exceptions: Disabled Features
Features that are temporarily disabled or taken out, but will be used in the future.


Helper functions
Utility functions that help with common tasks can be reviewed regularly to check if it needs to be removed. Disabled Features
Features that are temporarily disabled or taken out, but will be used in the future. Disabled Features Disabled Features Features that are temporarily disabled or taken out, but will be used in the future. Helper functions
Utility functions that help with common tasks can be reviewed regularly to check if it needs to be removed. Helper functions Helper functions Utility functions that help with common tasks can be reviewed regularly to check if it needs to be removed. Tools for Scanning Dead Code The following tools help detect and analyze unused code, imports, functions, variables, and dependencies. Choose tools based on your tech stack: ts-prune

Detects unused exported functions, constants, and types in TypeScript projects.
On Maintenance (no further update)


depcheck

Checks for unused npm dependencies and missing ones.


knip.dev (We are using this!)

Knip finds and fixes unused dependencies, exports and files in your JavaScript and TypeScript projects. Less code and dependencies lead to improved performance, less maintenance and easier refactorings. ts-prune

Detects unused exported functions, constants, and types in TypeScript projects.
On Maintenance (no further update) ts-prune ts-prune Detects unused exported functions, constants, and types in TypeScript projects.
On Maintenance (no further update) Detects unused exported functions, constants, and types in TypeScript projects. On Maintenance (no further update) depcheck

Checks for unused npm dependencies and missing ones. depcheck depcheck Checks for unused npm dependencies and missing ones. Checks for unused npm dependencies and missing ones. knip.dev (We are using this!)

Knip finds and fixes unused dependencies, exports and files in your JavaScript and TypeScript projects. Less code and dependencies lead to improved performance, less maintenance and easier refactorings. knip.dev knip.dev (We are using this!) Knip finds and fixes unused dependencies, exports and files in your JavaScript and TypeScript projects. Less code and dependencies lead to improved performance, less maintenance and easier refactorings. Knip finds and fixes unused dependencies, exports and files in your JavaScript and TypeScript projects. Less code and dependencies lead to improved performance, less maintenance and easier refactorings. unused dependencies, exports and files How to Scan and Remove Unused Code with knip knip Follow these steps to identify and safely remove unused code from your project using knip: knip Install knip (if not already installed):
yarn add -D knip
# or
npm install -D knip



Run the analysis:
yarn knip

Note: Replace yarn with your preferred package manager (npm, pnpm, etc.).


Review the list of unused files or exports:

Go through the list from top-down, starting with high-level components, constants, and utilities.
Search your codebase to verify whether each flagged file or export is truly unused.

If it's used elsewhere, skip it.
If it has no references, it’s safe to delete.






Remove confirmed dead code

Delete unused files, exports, or lines confidently after reviewing
Check with your teammates if the components/files is not used anymore or just temporarily not used



Validate your codebase:


Run linters and TypeScript checks to catch any issues:
yarn lint
npx tsc --noEmit



Start the development server to confirm everything still works:
yarn dev





Final step: Commit your changes with a clear message, e.g.:
git commit -m "chore: remove unused code and dependencies" Install knip (if not already installed):
yarn add -D knip
# or
npm install -D knip Install knip (if not already installed): Install knip yarn add -D knip
# or
npm install -D knip yarn add -D knip
# or
npm install -D knip Run the analysis:
yarn knip

Note: Replace yarn with your preferred package manager (npm, pnpm, etc.). Run the analysis: Run the analysis yarn knip yarn knip Note: Replace yarn with your preferred package manager (npm, pnpm, etc.). Note yarn npm pnpm Review the list of unused files or exports:

Go through the list from top-down, starting with high-level components, constants, and utilities.
Search your codebase to verify whether each flagged file or export is truly unused.

If it's used elsewhere, skip it.
If it has no references, it’s safe to delete. Review the list of unused files or exports: Review the list of unused files or exports Go through the list from top-down, starting with high-level components, constants, and utilities.
Search your codebase to verify whether each flagged file or export is truly unused.

If it's used elsewhere, skip it.
If it has no references, it’s safe to delete. Go through the list from top-down, starting with high-level components, constants, and utilities. top-down Search your codebase to verify whether each flagged file or export is truly unused.

If it's used elsewhere, skip it.
If it has no references, it’s safe to delete. Search your codebase If it's used elsewhere, skip it.
If it has no references, it’s safe to delete. If it's used elsewhere, skip it. If it has no references, it’s safe to delete. Remove confirmed dead code

Delete unused files, exports, or lines confidently after reviewing
Check with your teammates if the components/files is not used anymore or just temporarily not used Remove confirmed dead code Remove confirmed dead code dead code Delete unused files, exports, or lines confidently after reviewing
Check with your teammates if the components/files is not used anymore or just temporarily not used Delete unused files, exports, or lines confidently after reviewing Check with your teammates if the components/files is not used anymore or just temporarily not used Validate your codebase:


Run linters and TypeScript checks to catch any issues:
yarn lint
npx tsc --noEmit



Start the development server to confirm everything still works:
yarn dev Validate your codebase: Validate your codebase: Run linters and TypeScript checks to catch any issues:
yarn lint
npx tsc --noEmit



Start the development server to confirm everything still works:
yarn dev Run linters and TypeScript checks to catch any issues:
yarn lint
npx tsc --noEmit Run linters and TypeScript checks to catch any issues: yarn lint
npx tsc --noEmit yarn lint
npx tsc --noEmit Start the development server to confirm everything still works:
yarn dev Start the development server to confirm everything still works: yarn dev yarn dev Final step: Commit your changes with a clear message, e.g.:
git commit -m "chore: remove unused code and dependencies" Final step: Commit your changes with a clear message, e.g.: Final step: git commit -m "chore: remove unused code and dependencies" git commit -m "chore: remove unused code and dependencies" Getting rid of dead code might feel like a chore, but it’s totally worth it. Cleaner code means fewer headaches, faster builds, and easier debugging down the line. With the right tools and a step-by-step approach, it’s not that hard to keep your codebase in shape. If you’re working in a fast-paced company where keeping track of all the new code is challenging, making this part of your regular workflow is a must. If you have any other better approach or just want to share your own process, feel free to share in the comment! I would love to hear your thought!

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Everything You Need to Know About Dead Code

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