Using JavaScript object syntax
JSON is stricter than JavaScript object literals: use double-quoted keys, no comments, and no trailing commas.
JSON Formatter and Validator Online | Format, Minify, Debug
FormattingRuns in Your Browser (No Uploads)
Beautify or minify JSON with 2/4-space indentation and real-time validation that pinpoints exact line/column errors. Fast, private, and 100% in-browser.
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What to do next
Continue with a related workflow or open the next tool that usually follows this task.
Workflow guide
Convert CSV to JSON for spreadsheet data cleanup
Use this workflow when a spreadsheet export needs to become API-ready JSON, a fixture, or a structured dataset for debugging.
OpenRelated toolJSON Validator | Validate & Debug JSON Syntax
Live JSON validation with exact line/column errors—fully local in your browser.
OpenHow to Use This Tool
- 1
Choose Format (beautify) or Minify.
- 2
Paste or type JSON into the input area.
- 3
See live validation with exact line/column errors—or use Manual mode.
- 4
Pick indentation (2 or 4 spaces) and apply.
- 5
Copy or download the processed result.
When to Use This Tool
Debug REST API & GraphQL Responses
Pretty-print or minify API/GraphQL responses to inspect structure and troubleshoot quickly.
Validate Configuration Files
Validate package.json, tsconfig.json, and other config files with precise error locations.
Code Review & Documentation
Reformat compact JSON for readable pull requests and documentation snippets.
Minify JSON for Production
Minify JSON to reduce payload size and bandwidth while preserving data exactly.
Common Mistakes
Validating only after deployment
Paste configuration or API samples here before shipping so syntax errors are caught with line and column details.
Minifying before debugging
Beautify unfamiliar data before review; minify only when you need a compact payload for transport or storage.
Examples
Pretty-print an API response
A compact API response becomes readable, indented JSON that is easier to inspect during debugging or review.
Input
{"user":{"id":42,"roles":["admin","editor"]},"active":true,"lastLogin":"2026-05-13T09:30:00Z"}Output
{
"user": {
"id": 42,
"roles": [
"admin",
"editor"
]
},
"active": true,
"lastLogin": "2026-05-13T09:30:00Z"
}Minify a configuration object
Indented configuration JSON can be minified before embedding it in test fixtures, docs, or payload examples.
Input
{
"feature": "search",
"enabled": true,
"limits": {
"pageSize": 50,
"timeoutMs": 3000
}
}Output
{"feature":"search","enabled":true,"limits":{"pageSize":50,"timeoutMs":3000}}JSON & Validation Basics
JSON is a UTF-8 text format composed of objects and arrays; allowed types are string, number, boolean, null, object, and array.
RFC 8259 rules: double-quoted keys/strings, escaped control characters, and no trailing commas.
Parsing follows the standard to surface exact error locations; pretty-print/minify run in O(n) relative to input size.
Frequently Asked Questions
Q.What's the difference between JSON and JavaScript objects?
A. JSON is a text data format with a fixed set of types (string, number, boolean, null, object, array). JavaScript objects are runtime structures and can include functions, undefined, Symbols, etc.
Q.Can I use single quotes in JSON?
A. No. Per RFC 8259, keys and string values must use double quotes (").
Q.Are trailing commas allowed in JSON?
A. No. Valid JSON does not allow trailing commas after the last item of an array or object.
Q.Can this tool handle very large JSON files?
A. Yes—within browser memory limits. Modern devices typically handle several megabytes smoothly; switch to Manual mode for very large inputs.
Related workflow guides
Use these focused guides when you need a practical workflow before opening the tool.
Workflow guide
Convert CSV to JSON for spreadsheet data cleanup
Use this workflow when a spreadsheet export needs to become API-ready JSON, a fixture, or a structured dataset for debugging.
Workflow guideFix CSV and JSON conversion errors
Use this workflow when a spreadsheet export, API fixture, or CSV/JSON handoff fails because columns shift, headers disappear, characters look broken, or JSON will not parse.
Workflow guideFormat JSON for API debugging
Use this workflow when an API response is hard to read, a JSON payload fails validation, or a frontend error points to malformed structured data.
Workflow guideGenerate UUIDs for realistic test data
Use this workflow when you need realistic unique identifiers for examples, tests, seeded records, or temporary objects without exposing production IDs.
Workflow guideDetect text file encoding before import
Use this workflow when text looks garbled, CSV headers behave strangely, or an import job requires a known encoding such as UTF-8, UTF-16, ASCII, or a BOM-free file.
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