JSON Formatter & Minifier
Formats, validates and minifies JSON, pretty-printing or compacting the input.
Designed to process your files locally in your browser. Zerdly does not intentionally upload or store them unless this page says otherwise.
How to use this calculator
- Paste your JSON.
- Press Format to pretty-print, or Minify to compress.
How it works
Format indents the JSON so it's readable; Minify strips all whitespace to make it as small as possible. Both validate the JSON and report the first error.
Common mistakes
- Pasting JSON with trailing commas or single quotes — strict JSON needs double quotes and no trailing commas.
- Expecting it to fix logic errors — it formats and validates syntax, not your data's meaning.
Frequently asked questions
Does this send my JSON to a server?
No — formatting and validation run entirely in your browser, so sensitive payloads stay on your device.
Why won't my JSON parse?
Common causes are single quotes instead of double, trailing commas, or unquoted keys — the tool points to where parsing fails.
Why won't my JSON format?
It must be valid JSON — keys and strings need double quotes, and there can be no trailing commas.
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Cite this tool
Zerdly. (2026). JSON Formatter & Minifier. Retrieved from https://www.zerdly.com/tools/json-formatter/
Tip: Enter any known values to calculate the remaining results.
Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.