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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.
DeveloperFree tool

Use Postly for the next step

After formatting, keep the workflow moving. Turn the result into docs, release notes, or internal publishing workflows.

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Use the output from this tool in one workspace for social media publishing and email campaign publishing. Draft, schedule, publish, and keep the work moving without switching between disconnected tools.

Bulk and recurring postsCampaign-ready contentOne publishing workspace

Social media publishing

Plan, schedule, and publish posts across your connected channels.

Email campaign publishing

Create and publish campaigns for Mailchimp, Brevo, Kit, ActiveCampaign, and Beehiiv.

Built for conversion workflows

Capture the moment after someone creates, downloads, or audits something and move straight into publishing.