JSON Formatter & Validator
Format, validate, and analyze JSON with professional tools and insights.
JSON Formatting Examples
Unformatted Input
{"name":"John","age":30,"city":"New York"}Pretty Output
{
"name": "John",
"age": 30,
"city": "New York"
}Additional Examples
Formatting Minified JSON
Input:
{"name":"Alice","age":30,"city":"New York"}
Output:
{
"name": "Alice",
"age": 30,
"city": "New York"
}Converts a compact, single-line JSON string into a human-readable format with indentation.
Validating and Formatting Complex JSON
Input:
[ { "id": 1, "items": [ "apple", "banana" ] }, { "id": 2, "active": true, "config": null } ]
Output:
[
{
"id": 1,
"items": [
"apple",
"banana"
]
},
{
"id": 2,
"active": true,
"config": null
}
]Formats nested arrays and objects with consistent indentation, handling different data types (number, string, boolean, null).
Detecting Syntax Errors
Input:
{
"name": "Bob",
"age": 40 // Missing comma
"isStudent": false
}The tool will identify the missing comma after the 'age' field and report a validation error.
Examples
Beautify minified JSON
{"user":{"id":42,"name":"Ada","roles":["admin","editor"]},"active":true}{
"user": {
"id": 42,
"name": "Ada",
"roles": [
"admin",
"editor"
]
},
"active": true
}A compact, single-line API response reformatted with consistent 2-space indentation.
Minify for transport
{
"name": "webhook",
"url": "https://example.com/hook"
}{"name":"webhook","url":"https://example.com/hook"}Strips all whitespace to produce the smallest valid payload for shipping over the wire.
Invalid JSON is caught, not silently accepted
{
"id": 1,
"name": "Ada", // comments are not valid JSON
"active": true,
}JSON forbids comments and trailing commas — the validator pinpoints the offending line so you fix the real problem instead of chasing a generic parse failure downstream.
About this tool
Paste JSON and the formatter validates it, then renders it in the mode you choose: Pretty with an indent you set — 2 spaces by default or a custom width — or Compact, which minifies everything onto a single line for production payloads. When parsing fails, the error message is matched to a line and column so you can jump straight to the offending character.
Statistics update on every run: counts of objects, arrays, strings, numbers, booleans and nulls, the maximum nesting depth, and the formatted output's character, line and byte size. Beyond formatting there is a tree view for exploring structure, JSONPath queries for pulling matching values, text search with highlighting, and a compare pane that diffs your JSON against a second copy.
The tool accepts strict JSON only: comments, trailing commas, single-quoted strings and unquoted keys are rejected exactly as a production parser would reject them. All parsing and analysis happen in your browser, so API responses containing real data stay on your machine.
How to use this tool
Paste or upload
Paste JSON into the editor, upload a .json file, or start from one of the bundled samples.
Choose a mode
Pick Pretty for readability — adjusting the indent width if needed — or Compact to minify.
Fix reported errors
If validation fails, use the reported line and column to locate the syntax problem, correct it, and run the formatter again.
Inspect the result
Read the statistics, browse the tree view, run a JSONPath query, then copy or download the formatted output.
Use cases
Debugging API responses
Paste a raw API response and instantly read nested objects instead of squinting at a minified blob.
Editing config files
Format a .json config so you can edit it safely, then minify it back before deploying.
Reviewing large payloads
Search across and inspect the depth and size of big documents you'd otherwise struggle to navigate.
Validating hand-written JSON
Catch a missing comma or quote before your app or CI pipeline rejects the file.
What the formatter handles
| Feature | What it does |
|---|---|
| Validation | Catches missing commas, brackets, quotes and trailing characters |
| Pretty-print | Re-indents with consistent spacing for readability |
| Minify | Strips whitespace to produce the smallest valid payload |
| Statistics | Reports key count, nesting depth and document size |
| File upload | Loads large JSON files without pasting |
All processing is client-side — your JSON never leaves the browser.
Common mistakes
Mistake:Using single quotes around strings or keys.
Fix:JSON requires double quotes — "key" and "value", never 'key'.
Mistake:Leaving a trailing comma after the last item.
Fix:Remove the trailing comma; JSON forbids it, unlike JavaScript object literals.
Mistake:Adding // or /* */ comments.
Fix:JSON has no comments. If you need notes, keep them outside the file or switch to JSONC/JSON5 deliberately.
Mistake:Trusting formatted JSON without schema validation.
Fix:Formatting proves the syntax is valid, not that the shape matches your contract — validate types separately.
Frequently asked questions
Why is my JSON invalid?
The usual culprits are a trailing comma before a closing bracket, single quotes around strings, comments, unquoted keys, or bare constants such as NaN. The JSON grammar allows none of these, and the validator reports the first position that breaks it.
Can it minify JSON as well?
Yes. Select the Compact mode and the output collapses to one line with no unnecessary whitespace — handy for shrinking configuration files or payloads before shipping them.
Does it support comments (JSONC)?
No. Validation follows the strict JSON specification, so JSONC annotations must be stripped first; otherwise the parser reports them as syntax errors just like any runtime would.
Is my JSON uploaded anywhere?
No. Parsing, formatting, statistics and comparisons all run in your browser with the standard JavaScript engine, and nothing is transmitted to a server.
Related guides
TOML vs YAML vs JSON: Choosing the Right Config Format
Why Rust and Python both settled on TOML, what each format actually gives you, and how to validate your Cargo.toml without guessing.
Validating JSON Against a Schema: A Practical Guide to JSON Schema
What JSON Schema guarantees, how draft-07 works, and how instance paths identify fields that are missing, malformed, or the wrong type.
JSON Lines (NDJSON): Streaming JSON for Logs, Pipelines and LLMs
What makes one-object-per-line files different from JSON arrays, when NDJSON shines, and how to work with it in any language.
XML to JSON: Converting Legacy Data for Modern APIs
Why the API world moved from XML/SOAP to JSON, the attribute-handling quirks that still trip converters up, and how to bridge the two formats safely in a client-side tool.
References & standards
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