Instant Syntax Validation with Line & Column Indicators
Pinpoint parsing flaws immediately with precise line and column markers, saving precious time when debugging large API responses or configuration files.
JSON Formatter & Validator
Free online JSON Formatter and Validator. Clean, indent, minify, and inspect JSON payloads with line-by-line syntax error detection and tree navigation.
Indent:
Valid JSON Syntax
569 B•31 lines•19 keys•depth 4•5 objects•2 arrays
Input JSON
31 lines · 569 B
Formatted Result
31 lines · 569 B
Developer Scenario: Debugging an API Error Response and Prettifying Nested JSON
A software engineer receives a minified JSON response from a REST API endpoint containing an unexpected trailing comma that breaks the frontend parser.
| Raw Input | {"status":"error","code":400,"errors":[{"field":"email","message":"invalid"},]} |
| Validator Diagnosis | SyntaxError: Unexpected token ] in JSON at line 1 column 78 (trailing comma before array close). |
| Formatted & Fixed Output | { "status": "error", "code": 400, "errors": [ { "field": "email", "message": "invalid" } ] } |
💡 The validator points directly to the syntax flaw, allowing the engineer to fix the issue and inspect cleanly indented fields instantly.
How to use JSON Formatter & Validator
- 1
Paste your raw, minified, or unformatted JSON code into the editor, or click "Load Sample" to inspect an example.
- 2
Choose your formatting indentation (2 spaces, 4 spaces, or 1 tab), or click "Minify" to remove all redundant whitespace for compact payloads.
- 3
Review the real-time syntax validator for any errors with exact line and column locations, then copy the result or download it as a .json file.
Why use this tool?
Flexible Indentation & Minification Controls
Switch between 2-space, 4-space, tab indentation, or single-line minified JSON with a single click, perfectly tailored for production configs or documentation.
100% Client-Side Privacy & Zero Data Transmission
Your JSON payload is processed purely in your browser runtime. No API requests, database storage, or analytics tracking touch your proprietary data.
Continue your workflow
Need to inspect changes or differences between two JSON versions? Use the Compare two JSON objects side-by-side.
Working with HTML templates or web responses alongside JSON? Try the Format and beautify HTML code.
Passing JSON strings inside URL parameters or webhooks? Use the Encode or decode URL query parameters.
Need a line-by-line visual diff of text files? Check out the Compare arbitrary text diffs.
JSON Data Types and Syntax Rules Reference
Summary of standard RFC 8259 JSON primitives, containers, and formatting rules.
| Data Type | Example | Valid Syntax Rules | Common Pitfalls |
|---|---|---|---|
| String | "hello world" | Must be enclosed in double quotes (") | Single quotes ('...') are invalid in JSON |
| Number | 42, -3.14, 1e5 | Integers or floating-point decimals | Hexadecimal (0x10) or NaN are invalid |
| Boolean | true, false | Must be lowercase true or false | Capitalized True or False will cause errors |
| Null | null | Literal lowercase null | undefined is not a valid JSON value |
| Array | [1, 2, "three"] | Ordered list enclosed in brackets [] | Trailing commas after the last item are disallowed |
| Object | {"key": "value"} | Key-value pairs enclosed in braces {} | Keys must always be strings in double quotes |
Adhering to strict RFC 8259 standards ensures interoperability across all programming languages.
Frequently asked questions
Does the JSON Formatter support comments in JSON?
Standard JSON (RFC 8259) does not support comments (// or /* */). If your input contains comments, the validator will highlight them as syntax errors. Strip comments to produce valid standard JSON.
Can this tool sort keys alphabetically?
Yes. You can toggle key sorting to automatically organize object properties in alphabetical order, making comparisons and audits seamless.
Is there a limit on the file size of JSON I can format?
Because formatting executes in your browser memory via native JavaScript engine algorithms, you can comfortably format documents up to tens of megabytes.
What is the difference between Minify and Beautify?
Beautify introduces structured indentation and line breaks for human readability. Minify strips all unnecessary whitespace and newlines, maximizing transmission speed and minimizing file size.
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