JSON Formatter
Format, validate, and prettify JSON data online for API debugging and code review
Format, validate, and minify JSON instantly. Paste your JSON to see syntax errors highlighted in real time, beautify minified payloads for debugging, or minify for production. Runs entirely in your browser.
How to use JSON Formatter
Paste or type your JSON
Paste your JSON data into the input area on the left. It can be minified, beautified, or partially broken.
View the formatted output
The formatted, validated JSON appears on the right in real time. Syntax errors are highlighted with their line and column.
Copy or download
Click Copy to copy the formatted JSON to your clipboard, or Download to save it as a .json file.
Indent
What is JSON formatting?
JSON Formatter instantly pretty-prints and validates JSON data. Paste minified JSON and it will be reformatted with proper indentation, making it easy to read and debug. It also works as a JSON validator, highlighting syntax errors so you can fix malformed JSON quickly.
The formatter runs entirely client-side (see our processing model for details). It supports standard JSON as well as common extensions like trailing commas and JavaScript-style comments (JSON5). Output can be minified for production use or beautified for readability.
JSON (JavaScript Object Notation) is the most widely used data interchange format on the web. REST APIs, configuration files, NoSQL databases, logging systems, and message queues all use JSON extensively. When debugging API responses, inspecting webhook payloads, reviewing configuration files, or analyzing log entries, readable formatting with proper indentation is essential to understanding the data structure. This tool handles deeply nested objects, large arrays, and mixed data types, displaying them with consistent 2-space or 4-space indentation and syntax highlighting that distinguishes strings, numbers, booleans, and null values at a glance.
Beyond formatting, the validator catches common JSON errors that cause silent failures in production: missing commas between array elements, trailing commas after the last property (invalid in strict JSON), single-quoted strings (valid in JavaScript but not in JSON), unquoted property names, and mismatched brackets or braces. The error message pinpoints the exact line and column, saving minutes of manual scanning. For developers working with JSON daily, see our JSON formatting and debugging guide for advanced techniques including diff comparison, path extraction, and schema validation strategies.
Frequently asked questions
Does the JSON formatter validate my JSON?
Yes. The formatter checks your JSON against the JSON specification and shows an error message with the exact line and column if your input is invalid.
Can it handle very large JSON files?
Yes, the formatter works with large JSON files. Very large files (several MB) may take a moment to format, but there is no strict file size limit.
Why does my API return minified JSON that is hard to read?
APIs minify JSON to reduce payload size and speed up transfers. The formatting is stripped server-side before sending. Paste the response here to instantly beautify it with indentation for debugging and inspection.
Can I use it to minify JSON?
Yes. Click the Minify button to collapse the JSON into a single line with all unnecessary whitespace removed — useful for reducing payload size in APIs.
How do I check if my JSON is valid?
Paste your JSON into the input area. If it is valid, the formatted output appears instantly on the right. If it is invalid, an error message highlights the exact line and column where the problem is. Common issues include missing commas, unquoted keys, trailing commas, and mismatched brackets.
What is the difference between JSON and JSON5?
Standard JSON (RFC 8259) is strict: keys must be double-quoted, no trailing commas, no comments, and no single-quoted strings. JSON5 is a superset that relaxes these rules to match JavaScript object literal syntax — it allows comments, trailing commas, single-quoted strings, unquoted keys, and more. This formatter accepts JSON5 input for convenience but always outputs strict JSON for maximum compatibility.
How do I format a JSON API response for debugging?
Copy the raw API response from your browser DevTools Network tab, Postman, or curl output. Paste it into the input area and the formatted version appears instantly with proper indentation. This makes it easy to trace nested objects, verify field values, and spot unexpected null or missing properties. You can also use the URL Encoder to decode any percent-encoded values in the response URLs.
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Related guides
Working with JSON: Formatting, Validation, and Debugging
A practical guide to working with JSON data, covering formatting, validation, common errors, debugging techniques, and useful developer tools.
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