Does Next.js 15+ support ESLint Flat Config?

Yes, Next.js 15 and 16 fully support `eslint.config.mjs` with `@next/eslint-plugin-next`.

Can I still use Prettier with Flat Config?

Yes, simply import `eslint-config-prettier` and append it as the final object in your config array.

ESLint Legacy (.eslintrc) → ESLint v9 Flat Config (eslint.config.mjs)Automated Breaking Change Check

Migrate .eslintrc to ESLint v9 Flat Config

Convert legacy .eslintrc.json and .eslintrc.js configurations into ESLint v9 flat config (eslint.config.mjs) with typescript-eslint support.

From: ESLint Legacy (.eslintrc)

→

To: ESLint v9 Flat Config (eslint.config.mjs)

Source (ESLint Legacy (.eslintrc))

369 chars

Migrated Target (ESLint v9 Flat Config (eslint.config.mjs))

1ms379 chars

import js from '@eslint/js';
import tseslint from 'typescript-eslint';

export default tseslint.config(
  js.configs.recommended,
  ...tseslint.configs.recommended,
  {
    rules: {
    "no-unused-vars": "off",
    "@typescript-eslint/no-unused-vars": [
        "error"
    ],
    "no-console": "warn"
},
  },
  {
    ignores: ['dist/**', '.next/**', 'node_modules/**'],
  },
);

Detected Breaking Changes & Semantic Shifts (2)

Flat Config Root Object Structure

breaking

ESLint v9 replaces .eslintrc.* with an exported array of configuration objects in eslint.config.mjs.

Resolution: Export a default array using `tseslint.config()` or plain objects.

Plugin Import Semantics

breaking

Plugins must now be imported as JavaScript modules rather than referenced as string names.

Resolution: Import plugins directly: `import tseslint from "typescript-eslint";`.

How to Migrate from ESLint Legacy (.eslintrc) to ESLint v9 Flat Config (eslint.config.mjs)

1
Paste your legacy .eslintrc.json or .eslintrc.js content.
2
The migrator structures an exported array conforming to ESLint v9 flat config specification.
3
Plugins are mapped to modern ESM module imports instead of string identifiers.
4
Copy the output to `eslint.config.mjs` in your project root.

ESLint Flat Config Lint Check in CI

.github/workflows/lint.yml

name: Code Quality
on: [push, pull_request]
jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 20
      - run: npm ci
      - run: npx eslint .

Run Migration via Terminal CLI

Perform identical migration routines across entire directories or repositories in your local terminal:

devflow migrate eslintrc-to-flat-config -i .eslintrc.json -o eslint.config.mjs

npm / Node.jsBun Runtime

Migrate npm package.json to Bun Runtime & Scripts

Instantly migrate npm scripts, dependencies, and configurations to Bun. Optimize script execution speeds and strip obsolete transpilations.

Explore migration

Webpack 5Vite

Migrate Webpack 5 Config to Vite (10x Faster HMR)

Convert webpack.config.js bundles into lightning-fast Vite configs (vite.config.ts). Eliminate multi-minute cold starts and reload delays.

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Text Diff Checker

Compare two text blocks and highlight exactly what changed.

Frequently Asked Questions

Does Next.js 15+ support ESLint Flat Config?: Yes, Next.js 15 and 16 fully support `eslint.config.mjs` with `@next/eslint-plugin-next`.
Can I still use Prettier with Flat Config?: Yes, simply import `eslint-config-prettier` and append it as the final object in your config array.

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