Intro With the release of ESLint v9 , flat config is now the standard. But most TypeScript projects are still using outdated .eslintrc setups. If you're searching for: ESLint flat config TypeScript setup ESLint v9 configuration guide modern ESLint config example This guide shows a clean, scalable approach that works in real projects. Why ESLint flat config matters Flat config isn’t just a syntax change. It solves real problems: simpler configuration structure better performance easier composition across projects future-proof with ESLint v9+ If you're still using .eslintrc , you're working against the direction ESLint is moving. Where to put the config Create this file at the root of your project: eslint.config.js Enter fullscreen mode Exit fullscreen mode ESLint automatically detects this in v9.…