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Format & validate JSON

Validate JSON, add readable indentation or save compact output. Large numbers stay exact. Free, no sign-up, right in your browser.

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Result

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Questions about this tool

How does this tool work: Format & validate JSON?

Free, no sign-up, right in your browser. Paste JSON or load a file. Choose indentation and format. Invalid input produces an error message.

Does formatting change large JSON numbers?

No. The formatter changes only whitespace outside strings. Numbers are copied from the original without rounding. Value spelling and ordering are preserved too.

What inputs, outputs and limits apply?

Input: JSON text or a UTF-8 JSON file. Output: Validated, indented or compact JSON; JSON download. Limits: At most 500,000 characters, 2 MB per file and 100 nesting levels. Numbers, key order and string spelling are preserved. Duplicate keys are rejected. Comments are not JSON.

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Instructions, example and file limits

Formats, inputs and limits

Input: JSON text or a UTF-8 JSON file
Output: Validated, indented or compact JSON; JSON download
Limits & notes: At most 500,000 characters, 2 MB per file and 100 nesting levels. Numbers, key order and string spelling are preserved. Duplicate keys are rejected. Comments are not JSON.