Paste JSON → format, validate, minify, sort keys. Instant. Free. No signup. No data sent to any server.
JSON (JavaScript Object Notation) is the most widely used data interchange format on the web. APIs, configuration files, databases, and frontend-backend communication all rely on JSON. But raw JSON can be hard to read — especially when it comes from API responses or minified config files.
Our JSON Formatter & Validator helps you:
Unlike most online JSON tools, this formatter runs entirely in your browser. Your data is never sent to any server. Paste API keys, credentials, or sensitive data with confidence — nothing leaves your machine.
The most frequent JSON mistakes developers make:
Our validator catches all of these with precise error messages.
Paste your JSON into the input field and click "Format / Beautify." The tool instantly adds proper indentation and line breaks, making nested objects and arrays easy to read. You can choose between 2-space, 4-space, or tab indentation. The formatted output appears in the right panel, ready to copy.
Click "Validate" after pasting your JSON. If it's valid, you'll see a green success message. If there's an error, the validator shows the exact line and column number where the syntax error occurred — like a missing comma, extra bracket, or single-quoted string key. Fix the error and revalidate.
Formatting (beautifying) adds whitespace and indentation for human readability, increasing file size. Minifying removes all whitespace to reduce file size — critical for production APIs where every byte counts. A 10KB formatted JSON file might be 6KB minified, improving load times and reducing bandwidth usage.
Common JSON errors include: trailing commas after the last array/object item, using single quotes instead of double quotes, missing quotes around property keys, using undefined or NaN values (not valid in JSON), and including comments (JSON doesn't support comments). Our validator shows the exact error location.
With our tool, yes — it runs entirely in your browser with no server communication. API keys, credentials, and sensitive data never leave your machine. Always verify the tool is client-side before pasting sensitive data into any online formatter. This tool has zero server-side processing.