What does the JSON5 Formatter, Validator, and JSON Converter do?
Use this tool when you need a browser utility that parses relaxed JSON5 syntax and converts it to either normalized JSON5 or strict JSON. It accepts JSON5 with comments, trailing commas, single-quoted strings, and unquoted identifier keys and returns formatted JSON5, minified JSON5, or strict JSON. Results are deterministic for the same input except where cryptographic randomness, current time, or a live provider response is part of the task.
Use JSON5 for authoring convenience, JSON for interchange
Keep JSON5 where humans maintain configuration and the consumer explicitly supports it. Convert to strict JSON at compatibility boundaries such as web APIs.
How do you use it?
- Paste JSON5 or open a local .json5 file.
- Choose Format JSON5, Minify JSON5, or Convert to strict JSON.
- Run the tool, review any parse error, then copy or download the output.
Worked example
Convert relaxed configuration syntax
Input
{project: 'KitLumi', enabled: true,}Output
{
"project": "KitLumi",
"enabled": true
}JSON5 accepts the unquoted key, single quotes, and trailing comma; strict JSON output removes those extensions.
Common errors and fixes
| Symptom | Likely cause | Fix |
|---|---|---|
| The parser points at an unexpected token. | A quote, bracket, brace, or separator is missing. | Inspect the reported location and balance the surrounding syntax. |
| Another service rejects the original document. | That service accepts strict JSON rather than JSON5. | Use Convert to strict JSON before sending the value. |
Important behavior of JSON5 Formatter
JSON5 is not strict JSON, so APIs and JSON-only parsers may reject the original input.
Standards and implementation references
- JSON5 specification (opens in a new tab)Defines JSON5 syntax and its relationship to JSON.
- JSON5 reference implementation (opens in a new tab)Documents the parser and serializer used by the browser tool.
Frequently asked questions about JSON5 Formatter
Does the JSON5 Formatter upload my input?
No. Processing runs in the current browser tab, and the page does not send tool input to a KitLumi processing endpoint.
What input does the JSON5 Formatter accept?
It accepts JSON5 with comments, trailing commas, single-quoted strings, and unquoted identifier keys. The workspace checks the input and reports malformed or unsupported values before it produces a result.
What does the JSON5 Formatter produce?
It produces formatted JSON5, minified JSON5, or strict JSON. Copy and download controls appear when the output format supports them.
What limitation should I know?
JSON5 is not strict JSON, so APIs and JSON-only parsers may reject the original input.
What changed?
Added JSON5 validation, Readable formatting, Strict JSON conversion, Local file input, responsive controls, explicit runtime disclosure, and task-specific examples and limitations.