ESLint Flat Config Validator

Validate ESLint v9+ flat configuration files exported as JSON for structural correctness, language options, rules configuration, plugin setup, file/ignore patterns, and best practices. Uses pure Python 3 stdlib (json, argparse, re, os, sys) -- no external dependencies.

Since ESLint flat configs are JS/MJS/CJS (eslint.config.js), the validator works with JSON-exported snapshots. Export your config first:

node -e "import('./eslint.config.js').then(m => console.log(JSON.stringify(m.default)))" > eslint.config.json

Then validate the JSON output.

Commands

validate -- Comprehensive validation with all rules and summary

python3 scripts/eslint_flat_config_validator.py validate eslint.config.json
python3 scripts/eslint_flat_config_validator.py validate eslint.config.json --strict