JSON formatting/beautification & syntax error checking tool | ZeroTools

Validate, format and minify JSON in your browser while preserving number digits and key order. Try the sample, then copy the result or save a JSON file. The formatter does not send your input to a server.

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Client-Side Secure Execution

This tool executes entirely in your browser sandbox. None of your input strings, files, or configurations are uploaded to any external server.

Check an API response without changing its values

Try the sample, then choose Format. The ID 9007199254740993 keeps all its digits and 1.2300 keeps its decimal spelling. Minify removes whitespace outside strings. Copy the result or save it as a JSON file.

Editing the input clears the previous output so you do not accidentally copy an outdated result. If clipboard access is denied, select the output manually or use Save JSON.

What validation does and does not check

A single JSON value is accepted, including an array, string, number, boolean or null. Comments, trailing commas and multiple JSONL records are rejected. This checks syntax, not your application schema or the meaning of the values. Duplicate keys are preserved but may be interpreted differently by another application.

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Technical Specifications & Architecture

Syntax validation and value preservation The browser parser checks syntax. Output is then assembled from the original string, number and punctuation tokens, changing only whitespace outside strings. Parsed numeric values are never serialized, so large integers, trailing zeros, exponent notation and negative zero retain their spelling.

What is not changed Key order, duplicate keys, spaces within strings and escape sequences are preserved. This is not schema validation, duplicate-key resolution, sorting or canonicalization.

Output Copy and file download use the displayed result. Editing the input clears that result. The formatter does not send input or output to a server.

Frequently Asked Questions (FAQ)

A.
Choose two or four spaces. Tab indentation is not supported.
A.
Click Format or Minify to parse the input. Invalid JSON produces an error from the browser parser.
A.
No. The tool parses a single JSON value and displays text output.
A.
Formatting and minifying preserve number digits, trailing decimal zeros, exponent notation, duplicate keys and key order. A downstream application may still round numbers or overwrite duplicate keys.

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