✂️ Knip

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

export const myVar = true;

This is where ESLint stops: it handles files in isolation, so it does not know whether myVar is used somewhere else. This is where Knip starts: it lints the project as a whole and finds unused exports, files and dependencies.

It's only human to forget to remove things that you no longer use. But how do you find out? Where do you start finding things that can be removed?

The dots don't connect themselves. This is where Knip comes in:

• Finds unused files, dependencies and exports
• Finds used dependencies not listed in package.json
• Built-in support for workspaces (monorepos)
• Growing list of built-in plugins
• Use compilers to include other file types (e.g. .mdx, .vue, .svelte)
• Finds binaries and dependencies in npm scripts, and a lot more locations
• Finds unused members of classes and enums
• Finds duplicate exports
• Supports any combination of JavaScript and TypeScript
• Features multiple reporters and supports custom reporters
• Run Knip as part of your CI environment to detect issues and prevent regressions

Knip shines in both small and large projects. It's a fresh take on keeping your projects clean & tidy!

^{“An orange cow with scissors, Van Gogh style” - generated with OpenAI}

Installation

npm install -D knip

Knip supports LTS versions of Node.js, and currently requires at least Node.js v16.17 or v18.6.

Experimental: knowledge base

You might want to ask your questions in the Knip knowledge base (powered by OpenAI and 7-docs). This is an experimental knowledge base, answers may be incorrect.

Configuration

Knip has good defaults and you can run it without any configuration. Here's the default:

{
  "entry": ["index.js", "src/index.js"],
  "project": ["**/*.js"]
}

In addition to index.js, the following file names and extensions are also considered entry files:

• index, main and cli
• js, mjs, cjs, jsx, ts, mts, cts and tsx

This means files like main.cjs and src/cli.ts are automatically added as entry files.

Entry Files

Knip looks for entry files at those default locations, but also in other places:

• The main, bin and exports fields of package.json.
• Plugins such as for Next.js, Remix, Gatsby or Svelte add entry files.
• The scripts in package.json or other scripts may provide entry files.

Knip does this for each workspace it finds, trying to minimize the configuration to suit your project. In a perfectly boring world where everything is according to defaults you wouldn't even need a knip.json file at all.

Larger projects tend to have more things customized, and therefore probably get more out of Knip with a configuration file. Let's say you are using .ts files exclusively and have all source files only in the src directory:

{
  "$schema": "https://unpkg.com/knip@2/schema.json",
  "entry": ["src/index.ts"],
  "project": ["src/**/*.ts"]
}

The entry files target the starting point(s) to resolve the rest of the imported code. The project files should contain all files to match against the files resolved from the entry files, including potentially unused files.

Places where Knip looks for configuration (ordered by priority):

• knip.json
• knip.jsonc
• .knip.json
• .knip.jsonc
• knip.ts
• knip.js
• package.json#knip

So you can use a dynamic knip.ts with TypeScript if you prefer:

import type { KnipConfig } from 'knip';

const config: KnipConfig = {
  entry: ['src/index.ts'],
  project: ['src/**/*.ts'],
};

export default config;

Then run the checks with npx knip. Or first add this script to package.json:

{
  "scripts": {
    "knip": "knip"
  }
}

Use npm run knip to analyze the project and output unused files, dependencies and exports. Knip works just fine with yarn or pnpm as well.

Using workspaces in a monorepo? Please see workspaces for more details about configuring them.

Command-line options

$ npx knip --help
✂️  Find unused files, dependencies and exports in your JavaScript and TypeScript projects

Usage: knip [options]

Options:
  -c, --config [file]      Configuration file path (default: [.]knip.json[c], knip.js, knip.ts or package.json#knip)
  -t, --tsConfig [file]    TypeScript configuration path (default: tsconfig.json)
  --production             Analyze only production source files (e.g. no tests, devDependencies, exported types)
  --strict                 Consider only direct dependencies of workspace (not devDependencies, not other workspaces)
  --workspace              Analyze a single workspace (default: analyze all configured workspaces)
  --no-gitignore           Don't use .gitignore
  --include                Report only provided issue type(s), can be comma-separated or repeated (1)
  --exclude                Exclude provided issue type(s) from report, can be comma-separated or repeated (1)
  --dependencies           Shortcut for --include dependencies,unlisted,unresolved
  --exports                Shortcut for --include exports,nsExports,classMembers,types,nsTypes,enumMembers,duplicates
  --include-entry-exports  Include entry files when reporting unused exports
  -n, --no-progress        Don't show dynamic progress updates
  --reporter               Select reporter: symbols, compact, codeowners, json (default: symbols)
  --reporter-options       Pass extra options to the reporter (as JSON string, see example)
  --no-config-hints        Suppress configuration hints
  --no-exit-code           Always exit with code zero (0)
  --max-issues             Maximum number of issues before non-zero exit code (default: 0)
  -d, --debug              Show debug output
  --debug-file-filter      Filter for files in debug output (regex as string)
  --performance            Measure count and running time of expensive functions and display stats table
  --h, --help              Print this help text
  --V, version             Print version

(1) Issue types: files, dependencies, unlisted, unresolved, exports, nsExports, classMembers, types, nsTypes, enumMembers, duplicates

Examples:

$ knip
$ knip --production
$ knip --workspace packages/client --include files,dependencies
$ knip -c ./config/knip.json --reporter compact
$ knip --reporter codeowners --reporter-options '{"path":".github/CODEOWNERS"}'
$ knip --debug --debug-file-filter '(specific|particular)-module'

More documentation and bug reports: https://github.com/webpro/knip

Screenshots

Here's an example run using the default reporter:

This example shows more output related to unused and unlisted dependencies:

Reading the report

The report contains the following types of issues:

When an issue type has zero issues, it is not shown.

Getting too many reported issues and false positives? Read more about handling issues.

(1) The variable or type is not referenced directly and has become a member of a namespace. Knip can't find a reference to it, so you can probably remove it.

Output

Rules

Use rules in the configuration to customize the issue types that count towards the total error count, or to exclude them altogether.

• error (default): printed, adds to total error count (similar to the --include filter)
• warn: printed in faded/grey color, does not add to error count (i.e. the exit code)
• off: not printed, does not add to error count (similar to the --exclude filter)

Example:

{
  "rules": {
    "files": "warn",
    "classMembers": "off",
    "duplicates": "off"
  }
}

See reading the report for the list of issue types.

The rules are modeled after the ESLint rules configuration, and could be extended in the future. For instance, to apply filters or configurations only to a specific issue type.

Filters

You can --include or --exclude any of the reported issue types to slice & dice the report to your needs. Alternatively, they can be added to the configuration (e.g. "exclude": ["dependencies"]).

Use --include to report only specific issue types (the following example commands do the same):

knip --include files --include dependencies
knip --include files,dependencies

Use --exclude to ignore reports you're not interested in:

knip --include files --exclude classMembers,enumMembers

Use --dependencies or --exports as shortcuts to combine groups of related types.

See reading the report for the list of issue types.

When to use rules or filters

Filters are meant to be used as command-line flags, rules allow for more fine-grained configuration.

• Rules are more fine-grained since they also have "warn".
• Rules could be extended in the future.
• Filters can be set in configuration and from CLI, rules only in configuration.
• Filters have two groups (--dependencies and --types), rules don't have any grouping.

Ignore

There are a few ways to tell Knip to ignore certain packages, binaries, dependencies and workspaces. Some examples:

{
  "ignore": ["**/*.d.ts", "**/fixtures"],
  "ignoreBinaries": ["zip", "docker-compose"],
  "ignoreDependencies": ["hidden-package"],
  "ignoreWorkspaces": ["packages/ignore", "packages/examples/**"]
}

These can also be configured per workspace (except for ignoreWorkspaces).

What's next?

This is the fun part! Knip, knip, knip ✂️

As always, make sure to back up files or use Git before deleting files or making changes. Run tests to verify results.

• Unused files can be removed.
• Unused dependencies can be removed from package.json.
• Unlisted dependencies should be added to package.json.
• Unresolved imports should be reviewed.
• Unused exports and types: remove the export keyword in front of unused exports. Then you can see whether the variable or type is used within the same file. If this is not the case, it can be removed.
• Duplicate exports can be removed so they're exported only once.

🔁 Repeat the process to reveal new unused files and exports. Sometimes it's so liberating to remove things!

Getting too many reported issues and false positives? Read more about handling issues.

Workspaces

Workspaces are handled out-of-the-box by Knip. Every workspace is part of the analysis.

Workspaces are sometimes also referred to as package-based monorepos, or as packages in a monorepo. Knip uses the term workspace exclusively to indicate a directory that has a package.json.

Here's an example knip.json configuration with some custom entry and project patterns:

{
  "workspaces": {
    ".": {
      "entry": "scripts/*.js",
      "project": "scripts/**/*.js"
    },
    "packages/*": {
      "entry": "{index,cli}.ts",
      "project": "**/*.ts"
    },
    "packages/my-lib": {
      "entry": "main.js"
    }
  }
}

It might be useful to run Knip first with no or little configuration to see where it needs custom entry and/or project files. Each workspace has the same default configuration.

The root workspace is named "." under workspaces (like in the example).

Knip supports workspaces as defined in three possible locations:

• In the workspaces array in package.json (npm, Yarn, Lerna).
• In the workspaces.packages array in package.json (legacy).
• In the packages array in pnpm-workspace.yaml (pnpm).

Extra "workspaces" not configured as a workspace in the root package.json can be configured as well, Knip is happy to analyze unused dependencies and exports from any directory with a package.json.

The ignore, ignoreBinaries and ignoreDependencies options are available inside workspace configurations.

Here's some example output when running Knip in a workspace:

Use --debug to get more verbose output.

Plugins

Plugins tell Knip where to look for configuration and entry files, and if necessary have a custom dependency finder. Knip plugins are automatically activated, you don't need to install or configure anything.

To explain what they do, here's a quick example from a .eslintrc.json configuration file (for ESLint):

{
  "extends": ["airbnb"],
  "plugins": ["prettier"]
}

Knip's ESLint plugin reads .eslintrc.json and will return eslint-config-airbnb and eslint-plugin-prettier from this example to Knip, so it can tell you whether package.json is out of sync. In a nutshell, this is how plugins work. This is especially useful over time when such configuration files change (and they will)!

Knip contains a growing list of plugins:

• Ava
• Babel
• Capacitor
• Changesets
• Commitizen
• commitlint
• cspell
• Cypress
• ESLint
• Gatsby
• GitHub Actions
• husky
• Jest
• Lefthook
• lint-staged
• markdownlint
• Mocha
• Next.js
• npm-package-json-lint
• Nx
• nyc
• Playwright
• PostCSS
• Prettier
• Release It
• Remark
• Remix
• Rollup
• Semantic Release
• Sentry
• Storybook
• Stryker
• Stylelint
• Svelte
• Tailwind
• TypeDoc
• TypeScript
• Vite
• Vitest
• Webpack

Plugins are automatically activated. Each plugin is automatically enabled based on simple heuristics. Most of them check whether one of a few dependencies is listed in package.json. Once enabled, they add a set of config files for themselves and/or entry files for Knip to analyze.

• config files are given to the plugin's dependency finder
• entry files are given to Knip to include with the analysis of the rest of the source code

See each plugin's documentation for its default values.

config

Plugins usually include config files. They are handled by the plugin's custom dependency finder, which returns all dependencies referenced in the files it is given. Knip handles the rest to determine which of those dependencies are unused or missing.

entry

Other configuration files use require or import statements to use dependencies, so they don't need special handing and can be analyzed like any other source file. That's why these configuration files are also used as entry files.

Override plugin configuration

Usually, no custom configuration is required for plugins, but if your project uses custom file locations then Knip allows you to override any defaults. Let's take Cypress for example. By default it uses cypress.config.js, but your project uses config/cypress.js. Also, the default pattern for test files is cypress/e2e/**/*.cy.js, but your project has them at e2e-tests/*.spec.ts. Here's how to configure this:

{
  "cypress": {
    "entry": ["config/cypress.js", "e2e-tests/*.spec.js"]
  }
}

Multi-project repositories

Some repositories have a single package.json, but consist of multiple projects with configuration files across the repository (such as the Nx "intregrated repo" style). Let's assume some of these projects are apps and have their own Cypress configuration and test files. In that case, we could configure the Cypress plugin like this:

{
  "cypress": {
    "entry": ["apps/**/cypress.config.ts", "apps/**/cypress/e2e/*.spec.ts"]
  }
}

Disable a plugin

In case a plugin causes issues, it can be disabled by using false as its value (e.g. "webpack": false).

Create a new plugin

Getting false positives because a plugin is missing? Want to help out? Please read more at writing a plugin. This guide also contains more details if you want to learn more about plugins and why they are useful.

Compilers

Knip v2 introduces compilers that allow to include files that are not JavaScript or TypeScript in the process of finding unused or missing dependencies. For instance, .mdx, .vue and .svelte files come to mind.

Currently, this is only supported by using knip.js or knip.ts. Provide a compilers object in the configuration where each key represents the extension and the value is a function that takes the contents of these files as input and returns JavaScript or TypeScript as output. Here is an example that compiles .mdx files to JavaScript so these files and their imports and exports become part of the analysis:

import { compileSync } from 'mdx-js/mdx';

export default {
  compilers: {
    mdx: compileSync,
  },
};

Read Compilers for more details and examples.

Production Mode

The default mode for Knip is holistic and targets all project code, including configuration files and tests. Test files usually import production files. This prevents the production files or their exports from being reported as unused, while sometimes both of them can be removed. This is why Knip has a "production mode".

To tell Knip what is production code, add an exclamation mark behind each pattern! that is meant for production and use the --production flag. Here's an example:

{
  "entry": ["src/index.ts!", "build/script.js"],
  "project": ["src/**/*.ts!", "build/*.js"]
}

Here's what's included in production mode analysis:

• Only entry and project patterns suffixed with !.
• Only production entry file patterns exported by plugins (such as Next.js and Gatsby).
• Only the start and postinstall scripts (e.g. not the test or other npm scripts in package.json).
• Only unused exports, nsExports and classMembers are reported (not types, nsTypes, enumMembers).

Strict

Additionally, the --strict flag can be used to:

• Consider dependencies (not devDependencies) when finding unused or unlisted dependencies.
• Include peerDependencies when finding unused or unlisted dependencies.
• Ignore type-only imports (import type {}).
• Verify each workspace is self-contained: have their own dependencies (and not use packages of ancestor workspaces).

Plugins

Plugins also have this distinction. For instance, Next.js entry files for pages (pages/**/*.tsx) and Remix routes (app/routes/**/*.tsx) are production code, while Jest and Storybook entry files (e.g. *.spec.ts or *.stories.js) are not. All of this is handled automatically by Knip and its plugins.

Paths

Tools like TypeScript, Webpack and Babel support import aliases in various ways. Knip automatically includes compilerOptions.paths from the TypeScript configuration, but does not (yet) automatically find other types of import aliases. They can be configured manually:

{
  "$schema": "https://unpkg.com/knip@2/schema.json",
  "paths": {
    "@lib": ["./lib/index.ts"],
    "@lib/*": ["./lib/*"]
  }
}

Each workspace can also have its own paths configured. Note that Knip paths follow the TypeScript semantics:

• Path values are an array of relative paths.
• Paths without an * are exact matches.

Reporters

Knip provides the following built-in reporters:

• codeowners
• compact
• json
• symbol

Custom Reporters

When the provided built-in reporters are not sufficient, a custom reporter can be implemented.

Pass --reporter ./my-reporter from the command line. The data can then be used to write issues to stdout, a JSON or CSV file, or sent to a service.

Find more details and ideas in custom reporters.

Public exports

Sometimes a file that's not an entry file has one or more exports that are public and should not be reported as unused. Such variables and types can be marked with the JSDoc @public tag:

/**
 * Merge two objects.
 *
 * @public
 */

export const merge = function () {};

/** @public */
export const split = function () {};

Knip does not report public exports and types as unused.

Ignore exports used in file

In files with multiple exports, some of them might be used only internally. If these exports should not be reported, there is a ignoreExportsUsedInFile option available. With this option enabled, you don't need to mark everything @public separately and when something is no longer used internally, it will still be reported.

{
  "ignoreExportsUsedInFile": true
}

In a more fine-grained manner, you can also ignore only specific issue types:

{
  "ignoreExportsUsedInFile": {
    "interface": true,
    "type": true
  }
}

Include exports in entry files

When a repository is self-contained or private, you may want to include entry files when reporting unused exports:

knip --include-entry-exports

Knip will also report unused exports in entry source files and scripts (such as those referenced in package.json). But not in entry and configuration files from plugins, such as next.config.js or src/routes/+page.svelte.

Handling Issues

How to handle a long list of reported issues? Seeing too many false positives? Read more about handling issues describing potential causes for false positives, and how to handle them.

Comparison

This table is an ongoing comparison. Based on their docs (please report any mistakes):

✅ = Supported, ❌ = Not supported, - = Out of scope

Migrating from other tools

depcheck

The following commands are similar:

depcheck
knip --dependencies

unimported

The following commands are similar:

unimported
knip --production --dependencies --include files

Also see production mode.

ts-unused-exports

The following commands are similar:

ts-unused-exports
knip --include exports,types,nsExports,nsTypes
knip --exports  # Adds unused enum and class members

ts-prune

The following commands are similar:

ts-prune
knip --include exports,types
knip --exports  # Adds unused exports/types in namespaces and unused enum/class members

Projects using Knip

Many thanks to some of the early adopters of Knip:

• Abracabra
• Block Protocol
• Cursor
• DeepmergeTS
• eslint-plugin-functional
• freeCodeCamp.org
• is-immutable-type
• release-it
• Template TypeScript Node Package

Potential boost with --no-gitignore

Running Knip on large workspaces with many packages may feel a bit sluggish. Knip looks up .gitignore files and uses them to filter out matching entry and project files. This increases correctness. However, you might want to disable that with --no-gitignore and enjoy a significant performance boost. Depending on the contents of the .gitignore files, the reported issues may be the same. To help determine whether this trade-off might be worth it for you, first check the difference in unused files:

diff <(knip --no-gitignore --include files) <(knip --include files)

And to measure the difference of this flag in seconds:

SECONDS=0; knip > /dev/null; t1=$SECONDS; SECONDS=0; knip --no-gitignore > /dev/null; t2=$SECONDS; echo "Difference: $((t1 - t2)) seconds"

⏲️ Analysis on a large project went from 33 down to 9 seconds (that's >70% faster).

Knip

Knip is Dutch for a "cut". A Dutch expression is "to be geknipt for something", which means to be perfectly suited for the job. I'm motivated to make Knip perfectly suited for the job of cutting projects to perfection! ✂️

Really, another unused file/dependency/export finder?

As listed above, there are already some great packages available if you want to find unused dependencies OR unused exports. I love the Unix philosophy ("do one thing well"). But looking at what Knip does, I believe it's efficient to handle multiple concerns in a single tool. When building a dependency graph of the project, an abstract syntax tree for each file, and traversing all of this, why not collect the various issues in one go?

Contributors

Special thanks to the wonderful people who have contributed to this project: