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Developer tools

Format and validate JSON

Indent with two spaces; preserve all value tokens and member order.

Up to 100,000 UTF-16 units / 400,000 UTF-8 bytes. Editing clears the previous result.

Enter JSON to begin.

Large numbers, string escapes, key order and duplicate keys are retained. Duplicate keys can still be interpreted differently by other applications.

Data is processed in this browser and is not uploaded or saved.

Help & FAQs

Make JSON easier to read and check its syntax. Large numbers, repeated keys and the original input remain available for review.

How to process JSON

  1. Paste or type JSON.
  2. Choose two or four spaces, compact output or validation only, then select Process JSON.
  3. Review the syntax result, then copy or download the actual JSON.

Preserve the data you entered

Formatting changes structural whitespace only. Numbers such as 9007199254740993, -0 and 1e400 retain their exact spelling; numbers are not first converted to JavaScript values. Strings keep their escape sequences, and members retain their order and repetitions. No sorting, deduplication or Unicode normalization is applied.

Errors show a fixed syntax explanation and a one-based line and column. Columns count UTF-16 units; CRLF is one line break. Escaped Unicode code units are preserved, including isolated surrogate escapes that different consumers may handle differently. Actual incomplete UTF-16 input is rejected before UTF-8 export.

Input: 100,000 UTF-16 units / 400,000 UTF-8 bytes. Output: 300,000 units / 400,000 bytes. Maximum nesting depth: 128; maximum tokens: 50,000. Processing uses 45-second checkpoints and yields between bounded scanning slices. Indentation can expand the output beyond its limit; shorten the input or use compact/validation mode.

Common questions

Will large numbers or duplicate keys change?

No. Numeric and string tokens are kept as written. Duplicate object members and their order are retained. Duplicate keys remain ambiguous across consumers; this tool does not decide which value should win.

Does validation check a schema or repair JSON?

No. It checks JSON syntax within the published limits. Comments, trailing commas and JavaScript expressions are rejected. Schema, business meaning and automatic repair are outside its scope.

What does validation-only download contain?

The original valid JSON, including its whitespace. Formatting and compacting instead download their actual generated result. Data stays on this page and is not uploaded or saved.