Registry / devops / prettier-plugin-kotlin

prettier-plugin-kotlin

library2.1.0jsnpmunverified

Prettier plugin for Kotlin language formatting. v2.1.0 (latest) ditched the original JS-based printer in favor of kastree's Kotlin Writer, a significant breaking change from v1.x. The parser (kotato) is alpha-stage, based on kastree, and can parse most Kotlin code but has performance issues. Release cadence is irregular with long gaps. Key differentiator: integrates Kotlin formatting into Prettier's ecosystem, allowing uniform code style across JS/TS/CSS/Kotlin projects. Lacks stable and full Kotlin grammar support; not recommended for production.

devops serialization

npm install prettier-plugin-kotlin

github ↗package ↗

INSTALL

IMPORT

SIG · PRETTIER-PLUGIN-KO

prettier-plugin-kotlin

devopsjavascriptv2.1.0

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

default plugin registration

✓ prettier.config.js -> module.exports = { plugins: ['prettier-plugin-kotlin'] }

✗ import prettierPluginKotlin from 'prettier-plugin-kotlin'

Prettier automatically discovers plugins named 'prettier-plugin-*' in node_modules. No explicit import needed unless you pass plugins array manually (ESM compatible).

require (CommonJS)

✓ const prettier = require('prettier'); const code = prettier.format('fun main() {}', { parser: 'kotlin', plugins: [require('prettier-plugin-kotlin')] })

✗ const prettierPluginKotlin = require('prettier-plugin-kotlin'); prettierPluginKotlin.format(code)

Do not call the plugin directly. Pass it as a plugin to prettier.format(). The plugin does not expose its own format function.

ESM (type: module)

✓ import prettier from 'prettier'; const code = await prettier.format('fun main() {}', { parser: 'kotlin', plugins: ['prettier-plugin-kotlin'] })

✗ import * as prettier from 'prettier'

Prettier v3+ is ESM-only. Use dynamic import or top-level await. The plugin string is auto-resolved.

Demonstrates formatting a simple Kotlin function with Prettier using the Kotlin plugin in ESM mode.

// Ensure prettier and prettier-plugin-kotlin are installed // npm install prettier prettier-plugin-kotlin import prettier from 'prettier'; const code = `fun main(args: Array<String>) { println("Hello, World!") }`; const formatted = await prettier.format(code, { parser: 'kotlin', plugins: ['prettier-plugin-kotlin'], tabWidth: 2, semi: false }); console.log(formatted); // Expected output: // fun main(args: Array<String>) { // println("Hello, World!") // }

Debug

Known issues

breakingv2.0.0 replaced the JavaScript-based printer with a Kotlin-based one (kastree Writer). Output may differ significantly from v1.x.

fix

Reformat all Kotlin files with the new plugin version. Review diff of formatted files for regressions.

affects: >=2.0.0

gotchaParser (kotato) is alpha; may fail on complex Kotlin syntax (e.g., inline classes, contracts, multi-file inference).

fix

For production, use kotlinc or ktlint. Only use this plugin for experimental or simple projects.

affects: >=1.0.0

gotchaVSCode Prettier extension may not auto-detect the plugin for Kotlin files; formatOnSave may not work despite manual formatting succeeding.

fix

Restart VSCode after installing plugin. Set 'prettier.requireConfig': false if needed. See https://github.com/prettier/prettier-vscode/issues/395

affects: >=1.0.0

deprecatedv1.x plugin used a different printer; upgrade to v2.x for current support.

fix

Update to version 2.1.0: npm install prettier-plugin-kotlin@latest

affects: <2.0.0

Errors

Common errors & fixes

Cannot find module 'prettier-plugin-kotlin'

Plugin not installed or not in node_modules.

fix

Run 'npm install --dev prettier prettier-plugin-kotlin' in your project root.

Error: Cannot parse file. Unsupported syntax: ...

The kotato parser does not support all Kotlin syntax or the file contains errors.

fix

Simplify the code or fix syntax errors. For advanced features, use ktlint instead.

Cannot read properties of undefined (reading 'type')

Plugin is outdated or Prettier version mismatch.

fix

Update both prettier and prettier-plugin-kotlin to latest: npm install prettier@latest prettier-plugin-kotlin@latest

Upgrade

Version history

2.1.0latest on npm

Audit

Dependencies

prettierrequiredpeer dependency; plugin relies on Prettier to load and invoke it

Agent activity

8 hits · last 30 days

node

Resources

githubhttps://github.com/Angry-Potato/prettier-plugin-kotlin ↗

packagehttps://www.npmjs.com/package/prettier-plugin-kotlin ↗