Developer Tools
JSON Formatter
Validate and format one complete JSON value with deterministic two-space indentation.
Enter the values and review the result.
JSON document
Format one complete valid JSON value with deterministic two-space indentation.
Maximum 100000 UTF-16 code units. JSON grammar whitespace around the value is allowed; malformed syntax is not repaired.
Paste valid JSON, then format it.
Formatting model
The formatter passes the complete source to standards-compatible native JSON parsing. If parsing succeeds, it serializes the resulting value with JSON.stringify(value, null, 2). Generated line breaks are deterministic LF characters.
For example, {"name":"Ada","active":true} becomes a multi-line object with two spaces before each property. Arrays and JSON primitive values are formatted under the same rule.
Native JavaScript semantics
Formatting does not preserve the source document byte for byte. Original indentation, line endings, insignificant whitespace, escape spelling, and number spelling may change. Duplicate object keys are not retained as separate entries. Very large or highly precise numbers follow JavaScript number parsing behavior.
Assumptions and limitations
This tool validates syntax and improves readability. It does not repair malformed JSON, allow comments or trailing commas, parse JavaScript object literals, sort keys, minify, validate schemas, fetch network data, or process uploaded files. Review sensitive data before placing it into any browser tool.
Transparency note
Accuracy and limitations
Calzivo tools are built for practical estimates, conversions, and checks. Some tools use standard formulas or simplified assumptions, and results can be affected by input accuracy, rounding, units, local rules, or changing official requirements.
Results depend on the values you enter and any simplified assumptions used by the tool. Verify important results before making decisions or submitting official information.
Reference check
Sources and references
These references provide background context for the topic. They do not replace official advice or documents for personal decisions.
- RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format
Internet Engineering Task Force
- ECMA-404: The JSON Data Interchange Syntax
Ecma International
How to Use This Tool
Use these steps to enter the right inputs and interpret the result correctly.
Paste one complete JSON value into the input field.
Select Format JSON to validate the syntax and apply two-space indentation.
Review the complete formatted document.
Copy only the JSON output or reset the formatter.
Related Tools
Other helpful tools in the Developer Tools category.
Base64 Converter
Encode UTF-8 text as standard Base64 or strictly decode Base64 back to valid UTF-8 text.
Binary Converter
Convert exact non-negative integers between decimal and binary using BigInt-backed arithmetic.
Hex to RGB Converter
Convert opaque three- or six-digit hexadecimal colors to RGB, RGBA, and normalized uppercase hex.
Hex to Decimal Converter
Convert exact non-negative hexadecimal integers to plain decimal digits without scientific notation.
Related Guides
Background reading and explanations related to JSON Formatter.
Frequently Asked Questions
Common questions about JSON Formatter and how to read the result.
Does this repair invalid JSON?
No. Comments, trailing commas, single quotes, unquoted keys, and other malformed syntax are rejected.
What top-level values are accepted?
Valid objects, arrays, strings, numbers, booleans, and null are accepted.
Are duplicate object keys preserved?
No. Native JavaScript JSON parsing retains one value for a duplicate key, so separate duplicate entries are not preserved.
Does formatting preserve original whitespace and number spelling?
No. The document is parsed and serialized again with two-space indentation using JavaScript JSON semantics.
Does this validate a JSON schema?
No. It validates JSON syntax only and does not check a schema or application-specific structure.