JSON Formatter & Validator
Paste raw or messy JSON to beautify it with proper indentation, validate the syntax, or minify it down to a single line. The tool runs locally in your browser, so even sensitive payloads from APIs or logs stay on your machine. It's a great helper for backend developers, mobile engineers, QA testers and anyone working with REST APIs or configuration files.
How to Format JSON Online
Paste your raw or minified JSON into the Input box, choose an indentation style (2 spaces, 4 spaces or tab), then click Beautify. The formatted output appears in the Result box, ready to copy. Use Minify to compact JSON onto one line for API payloads or config files, and Validate to check syntax without changing the format.
What Is JSON?
JSON (JavaScript Object Notation) is the most widely used data exchange format on the web. It represents structured data as key-value pairs and arrays using plain text, making it readable by both humans and machines. REST APIs, configuration files, databases like MongoDB and front-end frameworks all use JSON heavily.
Common JSON Errors and How to Fix Them
| Error | Cause | Fix |
|---|---|---|
| Unexpected token | Trailing comma after last item | Remove the comma before } or ] |
| Unexpected end of input | Missing closing bracket | Add the missing } or ] |
| Unterminated string | Unescaped quote inside a string | Escape with \" |
| Expected property name | Keys not wrapped in double quotes | Change 'key' to "key" |
| Invalid escape character | Single backslash in string | Use \\ for a literal backslash |
Beautify vs Minify — When to Use Each
Beautify adds indentation and line breaks, making JSON easy to read and debug. Use it when reviewing API responses, editing config files or documenting data structures. Minify removes all whitespace, reducing file size. Use it before including JSON in production code, API requests or wherever bandwidth matters.
For encoding minified JSON into Base64 for transport, jump to our Base64 Encoder or URL Encoder.
Frequently Asked Questions
What does the JSON formatter do?
It parses your JSON, validates the syntax, and re-prints it with consistent indentation. You can also minify it down to a single compact line.
How are syntax errors reported?
If the JSON is invalid, the tool shows the parse error message produced by JSON.parse, which usually identifies the exact position of the problem.
Is my JSON sent to a server?
No. Parsing and formatting happen entirely in your browser using JavaScript. Confidential API responses and config data stay on your machine.
What indentation styles are supported?
You can choose 2 spaces, 4 spaces or tab indentation when beautifying. Minify removes all whitespace for the most compact output.