Free Online JSON Formatter and Validator
Format, beautify, minify, and validate JSON right in your browser. Browse nested data with a collapsible tree view, query values with JSONPath, sort keys alphabetically, and clean up JSONC with comments or trailing commas. Syntax errors are shown with the exact line and column.
Try this example
You received a messy single-line JSON response from an API and need to read it, find a specific value, and check whether the structure is what you expected.
{"user":{"id":42,"name":"Ada","tags":["math","computing"]},"version":1}- 1Paste the JSON into the input box. The tool parses it instantly and shows the formatted version below.
- 2Switch to Tree view to expand and collapse nested objects and arrays. This is much easier than scrolling through formatted text for deeply nested data.
- 3Type a JSONPath query like $.user.email or $.items[*].id to pull specific values.
- 4If you need to compare with another JSON file, open Sort keys and copy the result. Sorted JSON files diff cleanly in git or any diff tool.
What JSON is and why it became universal
JSON (JavaScript Object Notation) is a lightweight data interchange format that reads like plain text. It was formalized in the early 2000s as a simpler alternative to XML for API responses, and today it is the default format for almost every web API, configuration file, and NoSQL database document.
The format supports only six data types: objects (key-value pairs), arrays (ordered lists), strings, numbers, booleans, and null. Despite this simplicity, you can represent almost any structured data. That restraint is deliberate and is the reason JSON stays readable even for deeply nested data.
If you work with REST APIs, GraphQL responses, environment configs, or log output, you probably handle JSON dozens of times per day. Having a fast online JSON formatter handy is one of those small workflow investments that pays back every time you debug a malformed response.
Common JSON mistakes and how this tool helps
The single most common JSON mistake is a trailing comma: {"a": 1, "b": 2,}. Standard JSON rejects this. Many editors and LLMs produce it anyway because most programming languages allow trailing commas. Enable Tolerant mode to strip them automatically.
The second most common mistake is single quotes instead of double quotes. JSON requires double quotes on both keys and string values. {"name": "Ada"} is valid; {'name': 'Ada'} is not. Our parser reports this with a clear error message pointing to the exact position.
Another frequent issue is unescaped characters inside strings, especially newlines and quotes. If you copy a multi-line error message into a JSON field without escaping, parsing fails. The tool highlights the problem line and suggests what needs to be escaped.
Finally, structural issues like mismatched braces or brackets show up when you edit a nested document by hand. The tree view makes these visible instantly because nodes that fail to close are missing from the hierarchy.
When to minify versus when to format
Minification removes all whitespace and shortens the JSON to its smallest serialized form. Use it when sending data over a network (API responses, webhooks) or storing at scale (millions of database rows). For a typical JSON document, minification saves 30 to 50 percent of the byte size.
Pretty-printed (formatted) JSON is for humans. Commit formatted config files to git so diffs are readable. Use 2-space indentation for most documents and 4-space when nesting is shallow but line length matters. Tabs are supported but rarely used in modern codebases.
If you are storing JSON in a column that will be diffed by humans (think git or code reviews), also sort keys alphabetically. Two semantically identical documents with keys in different orders produce ugly diffs otherwise. The Sort keys button in this tool produces canonical output that diffs cleanly.
Privacy and data handling
This JSON formatter never sends your data anywhere. Parsing, validation, formatting, minification, tree rendering, and JSONPath queries all run inside your browser using native JavaScript. Open your browser developer tools, switch to the Network tab, and paste any JSON. You will see zero outbound requests during any operation.
This makes the tool safe for confidential production data: API keys inside response bodies, user PII in debug payloads, internal config with database credentials. Nothing leaves your device.
How to use
- 01Paste JSON into the input box (or click Load sample to try it).
- 02See the formatted output with stats. Switch to Tree view for collapsible browsing or Minified for the compact form.
- 03Use the JSONPath box to query nested data. Open Sort keys to get an alphabetically sorted version.
FAQ
What is JSONPath?▼
JSONPath is a query syntax for JSON, similar to XPath for XML. The supported subset includes $ (root), .name (property), ['name'] (bracketed property), [0] (index), [-1] (last), [*] (wildcard for arrays), and .* (wildcard for object keys). Example: $.users[*].email returns the email of every user.
What is tolerant mode?▼
Standard JSON does not allow comments or trailing commas. Tolerant mode strips // and /* */ comments and trailing commas before parsing, so you can paste JSONC, JSON5-ish, or config-file JSON without manually cleaning it.
Can I see exactly where my JSON is invalid?▼
Yes. When parsing fails, the error message includes the line and column of the problem (when the browser reports a position).
Is my JSON sent to a server?▼
No. Every operation including formatting, validation, JSONPath queries, and sorting runs entirely in your browser using native JavaScript. Open DevTools → Network and confirm zero requests.