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JSONValidator • Fixer • FormatterDiff • Undo

JSON Validator, Auto-Fixer & Formatter

Paste or upload any JSON dump. Detect problems, Fix with one click, compare changes in a side-by-side diff, undo fixes anytime, and export Human-Readable, Beautiful (sorted keys), or Compact JSON.

Client-side only JSONC tolerant One-click Fix

Input JSON

Indent
0 = single line (minified)
Sort Keys
Undo Limit
Max undo steps

Validator & Auto-Fix

Valid JSON.
Detected issues
  • Trailing comma(s)
    Remove trailing commas

Human Readable

Beautiful (sorted keys)

Compact (minified)

Size & Savings
Input
0 B
Readable
4 B
Δ 0%
Beautiful
4 B
sorted keys
Compact
4 B
Δ 0%

Tips

  • • Validator catches log/config issues (comments, trailing commas, smart quotes, unquoted keys, missing braces, noise).
  • • Fixer offers one-click auto-fix or granular fixes with a checklist.
  • • Diff shows a quick line-level comparison — and you can Revert Fix anytime.
  • • Formatter outputs Human-Readable, Beautiful (deep key sort), and Compact JSON.
  • • 100% client-side. For huge inputs, try the Compact output to reduce memory.