Your data, your browser.
Formatting and comparison run on your device. The tool does not upload or save your JSON.
A LITTLE CLARITY FOR YOUR DATA
Messy JSON.
Meet your workbench.
Format, explore, and compare. All in your browser.
No uploads. No accounts. Just the useful bits.
Your JSON stays on your deviceLarge numeric IDs stay exact, too.
Ctrl / ⌘ + Enter to run
Valid JSON
Syntax checks passed. No duplicate keys found.
Syntax validation only — this does not check your API schema or business rules.JSON · UTF-8 · Up to 1 MB
02 Make sense of it
Ready when you are
Compares values and structure, ignoring object key order.
Start with your own JSON, or try the example.
How to fix:
Showing the first issue detected. Correct it and run again to check for more. Your input is never changed automatically.Keep every digit.
Long numeric IDs and decimal values keep their original digits. Duplicate keys are flagged instead of silently discarded.
Less noise. More signal.
Compare JSON by structure. Ignore object key order and see additions, removals, and changed values with their paths.
THE TWO-MINUTE GUIDE
From a wall of text
to something readable.
How do I format and validate JSON?
Paste a JSON document or open a local .json file, then choose Format JSON. Choose 2 or 4 spaces for readability, or Minify for compact output. Validate checks syntax without changing your input. Use Copy or Download to take the result with you.
Why does my JSON show an error?
JSON requires double quotes around keys and strings. Trailing commas, comments, and single-quoted strings are not valid JSON. For example, {"name": "Ada", "active": true} is valid. Errors include a line, column, highlighted excerpt, and a suggested fix. Use Jump to error to select the problem in your input. The tool reports the first issue detected; run it again after correcting that issue. Formatting and validation reject duplicate keys so a value cannot disappear silently. Compare allows them with a visible warning and uses the last occurrence of each repeated key in the same object.
How does the tree viewer work?
After formatting, select Tree to explore nested objects and arrays. Expand a row to see its children. Large trees display up to 1,500 nodes; the complete result remains available in Code and Download. Files are limited to 1 MB and 120 nesting levels to keep the tool responsive.
What does JSON comparison check?
Paste the original on the left and the updated version on the right. Comparison displays both documents as formatted JSON with line numbers. Changed and removed original values are highlighted red; changed and added updated values are highlighted green. Switch to Change cards for individual paths and values. Each formatted preview shows up to 6,000 lines. Compare ignores object key order but respects array order. If a key appears more than once in the same object, comparison uses its last value and shows a warning; earlier occurrences are ignored. Paths use JSON Pointer notation: /items/0/name means the name of the first item. Numeric spelling is significant: 1 and 1.0 appear as a change. Results are limited to 500 differences.
Does it preserve large numbers?
Yes. Numbers are retained as their original text, without conversion to JavaScript floating-point numbers. This preserves IDs such as 9007199254740993 and long decimal values. Formatting can normalize string escapes and reorder integer-like object keys; it is not a byte-for-byte archival tool.