JSONLint is a free online JSON validator and formatter. Paste your JSON, click Validate, and get instant feedback: we highlight errors and show exactly where to fix them. No sign-up, no limits — your data never leaves your browser.

Use it to pretty-print messy API responses, minify configs for production, or check logs and config files. One click to copy the result. Works in any modern browser and respects your theme (light or dark).