How to Use the JSON Formatter
Paste your JSON into the input panel on the left. The tool instantly validates it and shows the formatted output on the right. Use the mode tabs to switch between operations:
- Beautify — Pretty-print JSON with configurable indentation (2 or 4 spaces) and optional alphabetical key sorting.
- Minify — Compress JSON to a single line by removing all whitespace. Ideal for APIs and configuration files where size matters.
- Validate — Check if your JSON is syntactically valid. Errors show the exact line and column number.
- Tree View — Browse the JSON structure as a collapsible tree. Click any node to expand or collapse it.
You can also drag and drop a .json file onto the input area, or use keyboard shortcuts: Ctrl+Enter to beautify and Ctrl+Shift+M to minify.
What Is JSON?
JSON (JavaScript Object Notation) is a lightweight data-interchange format that is human-readable and easy for machines to parse and generate. It is built on two universal data structures: key-value pairs (objects) and ordered lists (arrays). Almost every programming language has built-in support for reading and writing JSON.
JSON is the dominant format for REST APIs, configuration files, NoSQL databases, and data exchange between web applications and servers. It replaced XML as the preferred format for most web services due to its simplicity and smaller payload size.
Common JSON Syntax Errors
| Error | Cause | Fix |
|---|---|---|
| Unexpected token | Trailing comma after last item | Remove the comma before } or ] |
| Unexpected token ' | Single quotes around strings | Use double quotes: "key" not 'key' |
| Unexpected end of input | Missing closing bracket or brace | Ensure every { has a } and every [ has a ] |
| Unexpected token u | Using undefined (not valid JSON) | Use null instead |
| Bad escape character | Unescaped backslash in strings | Use \\ for literal backslashes |
| Unexpected number | Leading zeros like 007 | Remove leading zeros: 7 |
JSON vs XML Comparison
| Feature | JSON | XML |
|---|---|---|
| Syntax | Lightweight key-value pairs | Verbose with opening/closing tags |
| Data types | String, number, boolean, null, object, array | All values are strings (needs schema) |
| Readability | Easier for humans to scan | More verbose, harder to scan |
| Parsing speed | Faster (native in JavaScript) | Slower (requires DOM parser) |
| Comments | Not supported | Supported |
| Use cases | APIs, config files, web apps | Document markup, SOAP, legacy systems |
Keyboard Shortcuts
| Shortcut | Action |
|---|---|
| Ctrl+Enter / Cmd+Enter | Beautify JSON |
| Ctrl+Shift+M / Cmd+Shift+M | Minify JSON |
| Tab | Insert 2 spaces (in input editor) |
Frequently Asked Questions
Is this JSON formatter free?
Yes, completely free with no signup and no usage limits. All processing happens in your browser — nothing is sent to a server.
Is my data safe?
Your JSON never leaves your browser. There is no server-side processing, no logging, and no analytics tracking on the content you paste.
What is the maximum JSON size I can format?
There is no hard limit, but very large files (over 5 MB) may cause the browser to slow down. For best performance, keep files under 1 MB. Drag-and-drop file upload is limited to 5 MB.
Why does my JSON show an error?
The most common causes are trailing commas, single quotes instead of double quotes, unquoted keys, comments (not supported in JSON), and missing brackets. The error message shows the exact line and column to help you find the issue.
Can I format JSON with comments?
Standard JSON does not support comments. If your file has comments (like JSONC or JSON5), you need to remove them first. This tool validates and formats strict JSON per the ECMA-404 specification.
What does "Sort keys" do?
When enabled, all object keys are sorted alphabetically at every nesting level. This is useful for comparing two JSON objects or creating deterministic output for version control.
What is the difference between beautify and validate?
Both check if the JSON is valid. Beautify reformats the output with indentation and line breaks. Validate focuses on confirming validity and showing detailed error messages if the JSON is malformed.
Can I use this on mobile?
Yes. The layout stacks vertically on small screens. Paste JSON, choose a mode, and the output appears below.
How do I format JSON in the command line?
Use
python3 -m json.tool file.json or jq . file.json. This web tool provides the same functionality with a visual interface.Does this support JSON5 or JSONC?
No. This tool validates and formats standard JSON (ECMA-404 / RFC 8259). JSON5 and JSONC extend the spec with comments and trailing commas, which are not supported here.