Best Free Online Developer Tools to Use in 2026
A practical, opinionated list of the best free online developer tools worth using in 2026, organized by category so you can find what you need fast.
Aug 08, 2026
ESLint Config Generator
Generate ESLint configuration files visually.
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- ESLint Config Generator
Copy the config to eslint.config.js (flat) or .eslintrc.json (legacy).
What is ESLint?
ESLint is a static code analysis tool for JavaScript and TypeScript. It identifies problematic patterns, enforces code style consistency, and helps prevent bugs before they reach production. ESLint supports plugins for frameworks like React and Vue, and custom rule configurations.
This generator supports two config formats:
- Flat config (eslint.config.js) — The modern format introduced in ESLint v9. Uses JavaScript/ESM syntax.
- Legacy config (.eslintrc) — The traditional JSON/YAML/JS format. Suitable for ESLint v8 and below.
Frequently Asked Questions
Which preset should I choose?
Prettier is recommended if you use Prettier for formatting. Airbnb is popular for large teams. Standard is minimal and opinionated. Google follows Google's style guide.
What is the difference between flat and legacy config?
Flat config (ESLint v9+) uses JavaScript with export default and removes the cascading config behavior. Legacy config uses JSON/YAML/JS with extends and env.
Is my configuration data stored on a server?
No. All generation happens in your browser using JavaScript. Your configuration never leaves your device.
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