JSON Formatter & Validator
Paste messy JSON and get clean, indented output with clear validation errors — free, instant and private. Your data is processed in your browser and never uploaded.
100% in your browser — your data never leaves your device.
How to format and validate JSON
- Paste your JSON into the input box on the left.
- It is parsed and pretty-printed instantly in the output panel; pick an indent size if you want.
- If the JSON is invalid, the error message and position appear below so you can fix it.
- Click Copy to put the clean JSON on your clipboard.
Why format JSON?
Minified or hand-edited JSON is hard to read and easy to break. Formatting adds consistent indentation and line breaks so the structure is obvious, and validating it first catches the missing comma or stray bracket that would otherwise crash your app or API call.
Frequently asked questions
- Is my JSON uploaded to a server?
- No. Formatting and validation run entirely in your browser with the native JSON parser. Your data never leaves your device.
- How does the validator report errors?
- If the input is not valid JSON, the parser message is shown below the editor, including the character position where parsing failed, so you can jump straight to the problem.
- Can I choose the indentation?
- Yes. Pick 2 spaces, 4 spaces or a tab, and the output is re-formatted instantly to match.
- Does formatting change my data?
- No. Only whitespace and key ordering as written are affected — the values and structure stay exactly the same. Reformatting is lossless.