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JSON Formatter

Free online JSON formatter and validator with Monaco, JSONPath, TypeScript/YAML tools, diff, schema validation, tree view, and local processing.

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Paste JSON to format or validate it.

JSON Course

A structured introduction to JSON: syntax, types, parsing, generation, real-world patterns, and ecosystem tradeoffs.

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About this tool

DevCove JSON Formatter is a free online JSON formatter, validator, and beautifier for developers. Paste API responses, config files, or log output into the editor to pretty-print JSON with syntax highlighting, catch syntax errors with exact line and column markers, minify JSON for production, and explore valid data in a tree view. Everything runs locally in your browser, so tokens, payloads, and customer data never leave your device.

How to use this tool

Use this JSON formatter online when you need readable JSON fast—without installing an IDE extension or uploading sensitive data to a third-party server.

  1. Paste raw, minified, or copied JSON into the editor, drag and drop a .json file, or click Upload file.
  2. Watch the status bar while you type: valid JSON shows character, line, and size stats; invalid JSON shows an error with line and column markers in the editor.
  3. Click Format JSON to beautify with your chosen indent (2 spaces, 4 spaces, or tabs).
  4. Click Minify to remove whitespace and produce a compact single-line JSON string for APIs, headers, or environment variables.
  5. Use Sort keys to alphabetize object keys recursively—helpful before committing config files or comparing payloads.
  6. If parsing fails, try Repair JSON for common fixes such as trailing commas, then validate again before copying the result.
  7. Switch to Tree view to inspect nested objects and arrays when the document is valid.
  8. Open the Developer tools panel for JSONPath queries, TypeScript type generation, YAML conversion, JSON diff, and JSON Schema validation.
  9. Copy or Download the final JSON when you are ready to use it in your app, test suite, or documentation.

Features

This tool combines a professional code editor with practical JSON utilities that developers use every day:

  • Monaco-powered JSON editor with syntax highlighting, line numbers, code folding, and word wrap.
  • Real-time JSON validation as you type, with inline error markers and precise line/column messages.
  • Pretty-print (beautify) JSON with 2-space, 4-space, or tab indentation.
  • Minify JSON to reduce payload size for HTTP responses, URLs, and storage.
  • Sort object keys alphabetically at every nesting level for stable diffs and reviews.
  • Repair common JSON syntax problems locally, including many trailing-comma cases.
  • Tree view to navigate complex API responses and configuration structures.
  • Developer tools panel: JSONPath, JSON to TypeScript, JSON ↔ YAML, structural diff, and JSON Schema validation.
  • Background Web Worker validation for very large JSON files to keep the editor responsive.
  • Upload, download, copy, example, and clear actions built into the toolbar.
  • Character, line, and approximate size statistics in the status bar.
  • 100% client-side processing—no login, no upload, no server-side storage of your JSON.
  • Works well for REST API debugging, webhook payloads, package.json snippets, and CI config review.
  • Bilingual interface with SEO-friendly documentation and a linked JSON subject course.

FAQ

Is this JSON formatter free and private?

Yes. DevCove JSON Formatter is free to use. Formatting, validation, minifying, and repair all run in your browser, so your JSON is not sent to our servers.

How is a JSON formatter different from a JSON validator?

A JSON validator checks whether text follows the JSON specification. A JSON formatter also reformats valid JSON for readability. This tool does both: it validates as you type and formats or minifies when you ask.

Can it validate JSON as I type?

Yes. The editor validates JSON continuously (with a short debounce). Syntax errors are highlighted in the editor, and the footer shows the line, column, and parser message.

What is the difference between Format JSON and Minify?

Format JSON adds indentation and line breaks so humans can read nested data. Minify removes unnecessary whitespace to produce the smallest valid JSON string—useful for production payloads and size-sensitive transports.

Should I use 2 spaces or 4 spaces for indentation?

Both are valid. Many JavaScript projects and APIs use 2 spaces; some enterprise configs prefer 4. Pick the indent option that matches your team or target system, then format.

What can Repair JSON fix?

Repair JSON targets common mistakes such as trailing commas and some quote or bracket issues. It is a helper, not a guarantee—always review repaired output before deploying to production.

When should I use the Tree view?

Use Tree view after your JSON is valid to explore deep objects and arrays without scrolling through a long text file. It is especially helpful for large API responses.

Can I format JSON from an API response or log file?

Yes. Paste the response body or log excerpt directly into the editor, or upload a .json file. If the text is almost JSON (for example copied from JavaScript), try Repair JSON after validation fails.

Does this tool work offline?

After the page loads, core actions run locally in the browser. You can disconnect from the network and still format, validate, and copy JSON that is already in the editor.

Is there a file size limit?

There is no artificial upload limit imposed by DevCove. Very large documents may slow down the browser because parsing and rendering happen on your device.

What is JSONPath and when should I use it?

JSONPath is a query syntax for selecting values inside nested JSON, similar in spirit to XPath for XML. Use the JSONPath tab after your document is valid to test expressions such as $.items[*].id when exploring API payloads.

Can I compare two JSON documents?

Yes. Open the Diff tab, keep document A in the main editor, paste document B in the comparison field, and run Compare JSON. The tool reports created, removed, and changed paths using a structural diff.

Does the tool support JSON Schema validation?

Yes. Paste a draft-07 compatible JSON Schema in the Schema tab and validate the editor JSON against it. Schema validation runs locally and lists constraint failures when the document does not match.

Is there a JSON course for learning the format itself?

Yes. DevCove publishes a separate JSON subject course at /courses/json/ with lessons on syntax, types, parsing, and real-world patterns. The course teaches JSON as a data format—not button-by-button tool instructions.