JSON Formatter & Validator
How to Use This JSON Formatter
- Paste or load your JSONPaste your JSON into the input area on the left, or click "Load Sample" to try with example data. The tool accepts any valid JSON - objects, arrays, nested structures, and all standard JSON data types.
- Format (pretty-print) the outputClick Format to pretty-print your JSON with proper indentation. Choose between 2-space, 4-space, or tab indentation using the selector next to the Format button. The output appears with syntax highlighting - strings in green, numbers in blue, booleans in orange, and null values in red.
- Minify for productionClick Minify to compress your JSON into a single line with all unnecessary whitespace removed. This is useful for reducing payload size in API requests or configuration files.
- Validate for syntax errorsClick Validate to check whether your JSON is syntactically correct without reformatting it. If there's an error, the tool shows the exact line and column number where the problem was found, and highlights the error line in the input.
- Explore with Tree ViewUse Tree View to explore your JSON as a collapsible hierarchy. Click any object or array node to expand or collapse it. This is especially helpful for navigating deeply nested structures. Use "Expand All" and "Collapse All" to control the entire tree at once.
- Inspect stats and copy outputThe stats bar shows your JSON's type, key count, nesting depth, and size. Click "Copy" to copy the formatted or minified output to your clipboard.
All processing happens locally in your browser - your data is never uploaded anywhere.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight, text-based data interchange format. Despite its name referencing JavaScript, JSON is language-independent and used by virtually every modern programming language, API, and web service. Its simplicity and readability have made it the dominant format for data exchange on the web — which is why a good JSON formatter and JSON validator is a daily tool for most developers.
JSON's two building blocks
A JSON document contains two basic structures: objects (collections of key-value pairs enclosed in curly braces) and arrays (ordered lists of values enclosed in square brackets). Values can be strings (in double quotes), numbers, booleans (true or false), null, or nested objects and arrays. This recursive structure allows JSON to represent complex, deeply nested data.
Why JSON replaced XML
JSON emerged from Douglas Crockford's work in the early 2000s as a simpler alternative to XML. Where XML requires opening and closing tags, attributes, and schemas, JSON achieves the same data representation with far less markup. A JSON document is typically 30–50% smaller than its XML equivalent, making it faster to transmit and parse.
Where you'll encounter JSON
Common uses of JSON include REST API responses, configuration files (package.json, tsconfig.json), NoSQL database storage (MongoDB documents), and browser localStorage. When working with APIs, you'll frequently need to format JSON for readability during development and minify it for production to reduce bandwidth.
Strict JSON vs JavaScript objects
Strict JSON differs from JavaScript object literals in important ways: keys must be double-quoted strings, trailing commas are not allowed, single quotes are invalid, and comments are not supported. These restrictions often cause validation errors when developers paste JavaScript objects expecting them to be valid JSON.
JSON Formatter & Validator Features
- Pretty print JSONChoose 2 spaces, 4 spaces, or tab indentation for readable output.
- Minify JSONStrip every unnecessary byte for production payloads and config files.
- Validate JSONSpot invalid JSON with exact line and column numbers for the first syntax error.
- Syntax highlightingStrings, numbers, booleans, and null are color-coded for quick scanning.
- Tree viewExplore deeply nested objects and arrays with expand/collapse controls.
- Stats panelRoot type, key count, nesting depth, and byte size at a glance.
- Copy & paste shortcutsOne-click copy of formatted or minified output to your clipboard.
- Handles large filesFormats multi-megabyte JSON documents locally without uploading anything.
- Privacy-firstRuns entirely in your browser. API responses containing PII, tokens, and secrets never leave your device.
When Developers Reach for a JSON Formatter
- Debugging REST & GraphQL APIsPaste a minified response to read it, find a bug, and share a formatted version in Slack.
- Validating config filesCheck
package.json,tsconfig.json,composer.json, ESLint, Prettier, and Terraform JSON configs before committing. - Inspecting webhooksPretty-print Stripe, GitHub, Slack, and Shopify webhook payloads.
- Preparing test fixturesFormat mocks for Jest, Vitest, Playwright, and Cypress tests.
- Reviewing NoSQL documentsMongoDB, DynamoDB, Firestore, and CouchDB records.
- Reading localStorage / sessionStorageThe DevTools Storage panel shows raw strings; paste them here to read structure.
- Reviewing JWT payloadsAfter base64 decoding, the inner JSON claims become much easier to inspect when formatted.
- Comparing JSON diffsFormat both documents with identical indentation so a diff viewer lines up cleanly.
Common JSON Errors and How to Fix Them
- Trailing commas
{"a":1,}is invalid JSON. Remove the final comma. - Single quotes
'key'must be"key". JSON requires double quotes around keys and string values. - Unquoted keys
{a: 1}must be{"a": 1}. - Comments
// lineor/* block */comments are not allowed. Delete them or use JSON5/JSONC only with a tolerant parser. - Undefined / functionsOnly
null, strings, numbers, booleans, objects, and arrays are valid values. - Unescaped special characters
\\,\", and control characters inside strings must be properly escaped. - BOM or hidden whitespaceSome editors prepend a UTF-8 byte-order mark that breaks parsers. Strip it and revalidate.