JSON Formatter
JSON Formatter prettifies JSON in your browser and also parses Python-dict style input - single quotes, True, False, None - into valid JSON.
At a glance
- Accepts
- JSON or Python-dict style text you paste
- Outputs
- Indented valid JSON you copy or save as formatted.json
- Where it runs
- Entirely in your browser, on your device
- What leaves your device
- Nothing - what you type stays in this tab
- Limits
- No size or count cap; bounded by your device's memory
- Account
- Not required - there is no sign-up
- Price
- Free, with no watermark and no usage cap
JSON Formatter prettifies JSON so it's actually readable - paste in a blob, pick your indentation, and format it. It also recognizes Python-dict-style input (single quotes, True/False/None, unquoted keys) and converts it to valid JSON automatically before formatting. That conversion is regex-based rather than a full Python parser, so it covers the common cases but not every possible dict literal. Everything else runs in your browser via JSON.parse and JSON.stringify; nothing you paste is sent anywhere.
How to use it
- Paste your JSON - or a Python dictionary - into the text box.
- Choose 2 or 4 spaces for indentation.
- Click "Format" to prettify it.
- Copy it to your clipboard or download it as a .json file.
Frequently asked questions
Is my JSON uploaded anywhere?
No - formatting runs entirely in your browser with JSON.parse and JSON.stringify. Nothing you paste is sent to a server.
Does it only work with valid JSON?
No - if the input isn't valid JSON, it's automatically retried as a Python dictionary (single quotes, True/False/None, unquoted keys) and converted to proper JSON before formatting.
Can I choose the indentation?
Yes - pick 2 or 4 spaces from the dropdown before you click Format.
What happens if my input is invalid?
You'll get an alert saying the format is invalid, and your original text stays untouched in the box - nothing is overwritten or lost.
Can I save the formatted output?
Yes - the download button saves it as a .json file, and the copy button copies it straight to your clipboard.
Does formatting overwrite what I pasted?
Yes - once parsing succeeds, the Format button replaces the text box contents with the prettified version. Copy or download first if you need the original back.