UTILS.
Private by default
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JSON Formatter & Validator

Pretty-print, minify and validate JSON, with inline error messages.

Your files stay on this device

Files are processed in your browser, never uploaded. The site downloads code and assets to run the tools. No accounts or trackers.

Use Download to save this tool as one HTML file for offline use.

Privacy →

Your text and files stay on this device. Nothing is uploaded or saved by this tool.

Try a worked example

Example

Enter {"id":9007199254740993,"ok":true} and choose Format. The ID stays exactly 9007199254740993. Switch to Tree to inspect both properties, or choose Minify to remove formatting whitespace.

Keep in mind

Numbers, quoted text and key order are preserved. Comments and trailing commas are not valid JSON. Editing the input or settings clears the previous result. Copy and download always use the latest completed conversion.

About this tool

Paste JSON or open a UTF-8 file, then choose Format or Minify. Inspect the highlighted code or expand objects and arrays in Tree view. Invalid JSON includes an error location you can jump to. Large numbers and duplicate keys are preserved; duplicate keys are flagged because other software may handle them differently.

Input is limited to 5 MiB of UTF-8 text, output to 20 MiB and JSON nesting to 128 levels. Large code, tree and table previews are limited to keep the page responsive; copy and download include the complete result. Processing runs locally in a cancellable background worker, including in the downloaded offline tool.

To keep processing responsive, JSON and CSV accept up to 100,000 values or cells. SQL accepts up to 4,000 tokens and 100 nested levels.

Editing the input or settings clears the previous result. Copy and download always use the latest completed conversion.

Your text and files stay on this device. Nothing is uploaded or saved by this tool.

Frequently asked questions

How do I use this tool?
Paste JSON or open a UTF-8 file, then choose Format or Minify. Inspect the highlighted code or expand objects and arrays in Tree view. Invalid JSON includes an error location you can jump to. Large numbers and duplicate keys are preserved; duplicate keys are flagged because other software may handle them differently.
How does it handle my data?
Numbers, quoted text and key order are preserved. Comments and trailing commas are not valid JSON. Your text and files stay on this device. Nothing is uploaded or saved by this tool.
Can I use large files or work offline?
Input is limited to 5 MiB of UTF-8 text, output to 20 MiB and JSON nesting to 128 levels. Large code, tree and table previews are limited to keep the page responsive; copy and download include the complete result. Processing runs locally in a cancellable background worker, including in the downloaded offline tool. To keep processing responsive, JSON and CSV accept up to 100,000 values or cells. SQL accepts up to 4,000 tokens and 100 nested levels.

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