Free JSON Formatter & Validator
Pretty print, minify, and validate JSON data instantly. Syntax errors are highlighted with the exact line and column. All processing happens in your browser, so confidential API payloads and customer data never leave your device.
Adds indentation and line breaks for readability.
Output will appear hereExplain with AIFree
Schema, TS & Python typesGet a plain-English summary of your JSON plus ready-to-paste TypeScript and Python type definitions.
Tips
- Tree view — click chevrons to expand/collapse nested objects.
- Fix mode — pastes from JS / YAML / config files often need quote conversion.
- JSONPath — extract subset of a big API response.
- All processing in your browser — paste sensitive data safely.
What this formatter can do
Beautify
Add indentation and line breaks so nested structures become readable at a glance.
Minify
Strip whitespace to produce the smallest valid JSON — saves bandwidth on APIs and storage.
Validate
Point out exactly where syntax errors occur (line, column, expected token) so you can fix fast.
Most common JSON mistakes
- Trailing comma. Strict JSON does not allow a comma after the last element in an array or object.
- Single quotes. All strings and keys must use double quotes — single quotes are not valid JSON.
- Unquoted keys. JavaScript object literals allow this; JSON does not.
- Comments. JSON has no comments. Anything starting with // or /* */ is a syntax error.
- Special numbers. NaN, Infinity, and -Infinity are not valid in JSON. Use null or a string like "Inf" instead.
Who uses a JSON formatter?
Backend developers
Inspect API responses, debug failed requests, and copy clean JSON into tests or mocks.
Frontend developers
Understand the shape of a payload before writing TypeScript types or React state.
DevOps engineers
Format Terraform plans, Kubernetes manifests exported to JSON, and CI environment configs.
QA testers
Reproduce API issues by sharing readable JSON snippets with the dev team.
Frequently asked questions
What does 'beautify' mean for JSON?
Beautifying JSON adds newlines and indentation (usually 2 or 4 spaces) so the structure is easy for humans to read. The data itself is identical — only the whitespace changes. Minifying does the opposite: it removes all unnecessary whitespace to make the file smaller.
What are the most common JSON syntax errors?
Trailing commas after the last item, single quotes instead of double quotes, missing commas between items, unquoted property names, and curly/square bracket mismatches. The validator points to the exact line and column where each error occurs.
Does this tool support JSON5 or comments?
Standard JSON does not allow comments or trailing commas. JSON5 (a more lenient superset used in dev configs) does. This tool currently validates strict JSON only — for JSON5, strip comments first or use a JSON5 parser.
Is my data uploaded to a server?
No. JSON parsing and formatting happen entirely in your browser. Your API responses, customer data, or internal configs are never transmitted anywhere.
What is the largest JSON file I can format?
Practical browser limit is around 50 MB. Above that, parsing can freeze the tab. For very large files, use a streaming JSON tool like jq on the command line instead.
Other free tools
Format and validate JSON instantly — pretty-print, minify, query via JSONPath, and now AI-explain. Pop in any JSON payload and our AI describes what each field means + generates TypeScript and Python type definitions.
How to use
- 1Paste JSON into the input.
- 2Toggle pretty-print / minify in the toolbar.
- 3Use JSONPath ($.field.subfield) to extract specific values.
- 4Click 'Explain this JSON' for AI walkthrough + type generation.
- 5Copy the formatted output, or the generated TS / Python types.
Why use this tool
- Format, validate, query, and explain — four tools in one.
- AI type generation saves 20+ min of manual TS/Python typing.
- Sensitive field detection warns about 'password', 'apiKey', 'token' fields.
- All processing local — no JSON sent to servers (except optional AI explain).
Real-world examples
API response
Paste a Stripe API response → AI explains every field, flags 'apiKey' as sensitive, and outputs matching TS interface + Python @dataclass.
Config debugging
Paste package.json → instantly see structure, validate, copy clean version back to file.
Type generation
Paste a complex nested JSON → AI generates exactly-matching TypeScript Root interface + Python dataclass. Drop into your file.