How to Format and Validate JSON (Free Online Guide)

Whether you are debugging an API response or editing a config file, readable JSON saves time. This guide covers formatting, validating, and inspecting JSON — all in your browser.

Format (beautify) JSON

1. Open the JSON Formatter.
2. Paste your JSON.
3. Choose 2- or 4-space indentation and click Format.
4. Copy or download the clean result.

Validate JSON and find errors

Invalid JSON usually comes from a trailing comma, a single quote, or a missing bracket. Paste your data into the JSON Validator to see whether it is valid and exactly where the error is.

Common fixes:

• Use double quotes for keys and strings, never single quotes.
• Remove trailing commas after the last item.
• Escape special characters inside strings.

Inspect large JSON

For big payloads, a tree view is easier than scrolling. The JSON Viewer renders JSON as a collapsible tree so you can expand only what you need.

Shrink it for production

Before shipping, remove whitespace with the JSON Minifier to reduce payload size.

Frequently asked questions

Is my JSON uploaded? No. All processing happens in your browser.

What makes JSON invalid? Strict JSON disallows comments, trailing commas, and single quotes — the validator flags these.