JSON Formatter Online — Free JSON Beautifier, Validator & Minifier
JSON Formatter
Prettify, minify, and validate JSON data instantly.
Free online JSON formatter and beautifier. Paste your JSON, choose 2- or 4-space indentation, and format with optional key sorting. Validates syntax with precise line and column error pointers. Minify JSON for production use, repair malformed JSON (trailing commas, single quotes, bare keys), generate TypeScript interfaces, or extract all dot-notation key paths. Runs entirely in your browser — no data is ever sent to a server.
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Tags: json, format, prettify, validate, lint, minify
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How to JSON Formatter Online
Paste your JSON into the input area on the left, or upload a .json file using the upload button.
Choose your indentation size — 2 spaces or 4 spaces — and optionally enable Sort Keys to alphabetically order object properties.
Click the Format button or press ⌘↵ (Mac) / Ctrl+Enter (Windows) to prettify your JSON with syntax highlighting.
Use Minify to collapse the JSON to a single line for production use, or Validate to check for syntax errors with precise line and column numbers.
Copy the formatted output with ⌘⇧C, download it as a .json file, or use the Share button to generate a gzip-compressed shareable URL.
JSON Formatter Features
JSON formatter with configurable indentation: 2 spaces or 4 spaces to match your team's style guide.
Sort Keys option: alphabetically reorders all object keys for consistent, diff-friendly output.
JSON validator with precise error reporting — shows the exact line number and column of the syntax error.
JSON minifier: collapses formatted JSON to a single line, removing all unnecessary whitespace for production use.
JSON Repair: automatically fixes common JSON errors including trailing commas, single-quoted strings, bare (unquoted) keys, missing colons, and missing commas.
TypeScript type generator: infers TypeScript interface definitions from any valid JSON document.
Key Path extractor: lists all dot-notation key paths in the JSON, useful for writing JSONPath or jq queries.
Syntax highlighting with color-coded strings, numbers, booleans, null values, and keys.
Large-input warning with byte count — alerts you when the input may slow down formatting.
Shareable URLs: gzip-compresses your JSON into a URL parameter so you can share documents with teammates.
Works entirely in your browser — no JSON is ever sent to any server. Your data stays completely private.
Keyboard shortcuts for power users: ⌘⇧F to format, ⌘⇧M to minify, ⌘⇧V to validate, ⌘⇧K to clear.
Frequently Asked Questions
- Is this JSON formatter free?
- Yes, DevFlow JSON Formatter is completely free with no usage limits. All formatting, validation, minification, and repair runs directly in your browser.
- Is my JSON data safe?
- Your JSON is processed entirely in your browser using pure JavaScript. No data is ever transmitted to a server. Your JSON stays on your machine.
- What does JSON formatting do?
- JSON formatting (also called prettifying or beautifying) takes a compact or unindented JSON string and reformats it with consistent indentation, line breaks, and spacing, making it human-readable and easier to debug.
- What is JSON minification?
- JSON minification collapses a formatted JSON document to a single line by removing all unnecessary whitespace, newlines, and indentation. Minified JSON is smaller in file size and is commonly used in API responses, configuration files, and environment variables.
- How does JSON validation work?
- The validator uses the native JSON.parse() function to check for strict RFC 8259 compliance. If the JSON is invalid, it reports the exact error message along with the line number and column position of the problem so you can locate and fix it instantly.
- What does JSON repair fix?
- The repair function attempts to fix common handwritten or copy-pasted JSON mistakes: trailing commas after the last array or object element, single-quoted string values or keys, unquoted (bare) property keys, missing colons between keys and values, and missing commas between items.
- How does TypeScript type generation work?
- The TS Types feature analyses the structure of your JSON and infers a TypeScript interface (or type alias for arrays). It handles nested objects, arrays, optional fields where some entries have properties others don't, and union types for mixed-type arrays.
- What are JSON key paths?
- Key paths list every leaf and intermediate key in a JSON document using dot-notation (e.g. user.address.city). This is useful for writing JSONPath queries, jq filters, or when you need a quick overview of the document schema.
- Can I upload a JSON file?
- Yes. Click the upload icon in the input panel header to select a .json or .txt file from your computer. The file contents are loaded into the input area for formatting.
- Does it work offline?
- Yes. All formatting logic is bundled with the page as pure JavaScript. Once the page has loaded, the JSON Formatter works without an internet connection.
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