JSON Validator & Formatter
Validate JSON for errors and format it with custom indentation — all in one tool.
Frequently Asked Questions
What JSON errors does the validator detect?
Any syntax error — missing commas, unquoted keys, trailing commas, mismatched brackets, invalid escape sequences, and more. The error message includes the line and column number where parsing failed.
Can I format minified JSON?
Yes. Paste any valid JSON — minified, partially formatted, or deeply nested — and the formatter outputs a clean, indented version.
Is my JSON data sent to any server?
No. All validation and formatting happens entirely in your browser using built-in JavaScript. Your data never leaves your device.
Which indentation style should I use?
2 spaces is the most common choice in JavaScript and web projects. 4 spaces is standard in Python and Java. Tabs are preferred in some Go and C style guides. Choose based on your project's convention.
Why does JSON not allow trailing commas?
JSON strictly follows the RFC 8259 specification, which does not permit trailing commas after the last element in an object or array. Many JSON parsers will reject them as a syntax error.
JSON Validator & Formatter — Check and Prettify JSON Instantly
JSON (JavaScript Object Notation) is the universal data interchange format used by virtually every web API, configuration file, and modern application. A single misplaced comma, unclosed bracket, or unquoted key causes the entire document to become unparseable — and tracking down that error by eye in a large blob of minified JSON is painful.
Our JSON Validator parses your input instantly and reports the exact line number and column where the syntax breaks. No more counting braces manually or squinting at a wall of text. The error message tells you precisely where the problem is so you can fix it in seconds.
The JSON Formatter takes valid JSON and outputs a clean, human-readable version with consistent indentation. Choose from 2 spaces (the most common convention for web projects), 4 spaces (popular in Python and Java communities), or a tab character (preferred in some style guides). The formatted output is fully copyable with a single click.
Both features run entirely in your browser. Your JSON data is never sent to any server — whether it contains API keys, personal data, database records, or proprietary configuration, it stays completely private. No account is needed, no rate limits apply, and results are instant regardless of document size.
Common uses include: validating API responses before parsing them in code, debugging configuration files that refuse to load, prettifying minified JSON for readability, checking JSON payloads in Postman or curl responses, formatting JSON before committing it to version control, and exploring the structure of unfamiliar data.
How to Use the JSON Validator & Formatter
- Select the "Validate" tab to check JSON for errors, or "Format / Prettify" to reformat it.
- Paste your raw JSON into the input box.
- In Validate mode: any errors are shown instantly with line and column numbers.
- In Format mode: choose your preferred indentation (2 spaces, 4 spaces, or Tab), then click "Format JSON".
- Copy the formatted output with the Copy button.
Related Tools
Word Counter
Count words, characters, sentences, and paragraphs in your text instantly.
UUID Generator
Generate version 4 UUIDs (Universally Unique Identifiers) instantly. Generate up to 20 at once and copy with one click.
Random Password Generator
Generate strong, secure random passwords with custom length and character options.