JSON Formatter & Validator
Paste JSON, format it, minify it, or check why it will not parse. Everything runs in your browser.
Formatted JSON will appear here...How to use
Paste raw JSON into the input area and click Format. Valid JSON gets 2-space indentation. Invalid JSON shows the parse error so you know where to start looking.
Features
Validation: detects JSON syntax errors
Pretty Print: Formats with consistent 2-space indentation
Minify: Compress JSON by removing whitespace
Copy: One-click copy to clipboard
When this tool helps
Minified JSON is fine for machines and miserable for people. This tool is useful when an API response looks like one endless line, a config file will not parse, or a webhook payload needs a quick sanity check. Paste it, format it, fix the obvious issue, move on.
Examples
Example 1: Debugging an API Response
A developer receives a minified 500-character API response like {"users":[{"id":1,"name":"Alice","roles":["admin","editor"]},...]}. Pasting it into the formatter reveals a clean, nested structure showing 3 users with their roles and permissions, making it immediately clear which user has which access level.
Example 2: Finding a Syntax Error
A configuration file fails to parse. Pasting the JSON into this tool reveals "Unexpected token at position 247", a trailing comma after the last array item. The developer removes the comma, re-formats, and the config now validates. Without this tool, finding that one comma in 300 lines would take much longer.
Example 3: Minifying for Production
A developer has a 4KB formatted JSON configuration file used in a web application. Using the Minify function reduces it to 2.7KB by stripping whitespace, a 33% reduction in file size. For applications sending many JSON payloads, this bandwidth savings adds up a lot over time.
Things to watch
- •JSON keys must be in double quotes, single quotes or unquoted keys are the most common syntax errors developers encounter.
- •Trailing commas after the last item in an array or object are invalid in JSON, even though JavaScript allows them.
- •JSON does not support comments, if you need comments in config files, consider JSONC or YAML instead.
- •Large numbers in JSON (over 2^53) may lose precision in JavaScript, use strings for very large IDs or financial amounts.
- •When copying JSON from logs, watch for escaped characters like \n and \" that may need to be unescaped first.
Common questions
- What is valid JSON?
- Valid JSON must follow strict syntax rules: data is wrapped in curly braces (objects) or square brackets (arrays), keys must be strings in double quotes, values can be strings, numbers, booleans, null, objects, or arrays, and commas separate items. No single quotes, trailing commas, or unquoted keys are allowed.
- What does minifying JSON do?
- Minifying JSON removes all unnecessary whitespace (spaces, tabs, line breaks) while keeping the data intact. This reduces file size a lot, making JSON faster to transmit over networks. The trade-off is that minified JSON is harder for humans to read.
- Can I format nested JSON?
- Yes, this formatter handles deeply nested JSON structures with arrays inside objects, objects inside arrays, and multiple levels of nesting. Each level is indented consistently for easy readability, and any errors in the nested structure are clearly reported.
- What are common JSON syntax errors?
- The most frequent JSON errors are: trailing commas after the last item in an array or object, using single quotes instead of double quotes for keys and strings, unquoted property names, comments (JSON does not support them), and missing commas between items. This formatter pinpoints the exact error location to help you fix issues quickly.
- How large of a JSON file can this tool handle?
- This tool runs entirely in your browser using JavaScript, so it can handle JSON files up to several megabytes without issues on modern devices. For very large files (50MB+), you may experience a brief delay during parsing. Since everything processes locally, there are no server upload limits or file size restrictions.