JSON Formatter & Validator
Format, beautify, and validate JSON instantly. Minify, set custom indentation, and catch syntax errors. Free, private, and runs entirely in your browser.
Free Online JSON Formatter & Validator
Working with JSON data? SmarterSources' JSON Formatter lets you beautify, minify, and validate JSON instantly. Whether you are debugging an API response, formatting a configuration file, or checking JSON syntax, this tool handles it all. Everything runs 100% in your browser — your data is never sent to any server.
How It Works
Paste your JSON into the input area and click "Format / Beautify" to pretty-print it with proper indentation. Use "Minify" to remove all whitespace for compact storage or transmission. The "Validate" button checks your JSON for syntax errors and reports the exact position of any issues, making it easy to find and fix problems.
Customizable Indentation
Choose between 2 spaces, 4 spaces, or tab characters for indentation. The default is 2 spaces, which is the most common convention for JSON files. Four spaces is popular in Python-heavy projects, while tabs let each developer set their preferred visual width.
JSON Stats at a Glance
After formatting, the tool displays useful statistics: the number of top-level keys (for objects) or items (for arrays), the maximum nesting depth of your data, and the total data size. These metrics help you understand the structure and complexity of your JSON at a glance.
Frequently Asked Questions
What is JSON?
JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write, and easy for machines to parse and generate. JSON is the most common format for API responses, configuration files, and data storage on the web.
What does "beautify" or "pretty print" mean?
Beautifying JSON means adding proper indentation and line breaks to make the data structure easy to read. Minified JSON (all on one line, no spaces) is efficient for machines but hard for humans to parse. Pretty-printing formats it with clear visual hierarchy.
Why does my JSON fail validation?
Common JSON errors include trailing commas after the last item in an object or array, using single quotes instead of double quotes, unescaped special characters in strings, and missing or extra brackets or braces. The error message shows the exact position where the parser found the problem.
Is my data safe?
Yes. All JSON processing happens entirely in your browser using JavaScript. Your data never leaves your device. SmarterSources does not collect, store, or transmit any data you enter into this tool.
What is the difference between JSON.stringify and JSON.parse?
JSON.parse converts a JSON string into a JavaScript object. JSON.stringify converts a JavaScript object back into a JSON string. This formatter uses both: it parses your input to validate it, then stringifies it with indentation to produce the formatted output.
Can I format large JSON files?
Yes. Since processing happens in your browser, the tool can handle large JSON payloads. Performance depends on your device's memory and processing power, but most devices can handle files up to several megabytes without issues.