JSON Formatter & Validator
Paste your JSON to format, validate, and beautify it instantly.
JSON parsing method and data-loss boundaries
Formatting is performed by parsing the input as JSON and serializing the resulting value with the selected indentation. This validates JSON syntax, but it does not validate a business schema or prove that fields contain correct data. Minification removes insignificant whitespace only after a successful parse.
Methodology
- The parser requires JSON syntax: double-quoted strings, valid escapes, and no trailing commas or comments.
- Formatted output serializes arrays and object members with the requested indentation.
- Minified output serializes the same parsed value without presentation whitespace.
- An error identifies invalid syntax instead of trying to repair ambiguous input automatically.
Worked review example
Input {"active":true,"count":3} formats predictably. JavaScript-style input containing single quotes, undefined, or a trailing comma is not valid JSON and should be corrected at the source. A duplicated object key is especially risky: parsers may retain only one value, so formatting should not be used as a preservation step for malformed records.
Test coverage and expected behavior
Test coverage includes objects, arrays, primitives, escaped Unicode, nested structures, empty input, trailing commas, comments, and malformed strings. Verification covers parse-format-parse equivalence for valid samples. Schema correctness, numerical meaning, and field-level requirements remain outside the tool.
Decision checklist before using the output
Treat successful formatting as syntax validation only. Before using the result, identify the schema owner and check required fields, allowed types, ranges, enumerations, and unknown-property policy. For financial identifiers, account numbers, and large database keys, confirm whether they should be JSON strings rather than numbers to avoid precision loss. Preserve the original when duplicate keys are possible, because a parse-and-serialize cycle may discard information. Compare a representative record with the producer and consumer, including null, empty string, zero, false, missing property, and an empty array; those states often have different business meanings. Large API responses are better inspected with a streaming or schema-aware tool. Never paste production credentials or personal records into an unapproved utility. This formatter is appropriate for small diagnostics, examples, and local browser validation.
Important limitations
- Very large integers can exceed JavaScript’s exact numeric range.
- Duplicate object names have unpredictable interoperability and may collapse during parsing.
- Property order should not be treated as semantic meaning.
- Secrets and personal records should not be pasted into unapproved browser tools.
Sources and specifications
These references define the relevant format or browser behavior. They do not endorse WordCaseFix.
Last reviewed: August 6, 2026