JSON Formatter Guide

Quick answer

Paste valid JSON into the input area, and the formatter rewrites it with readable two-space indentation. Use the format action to pretty-print, the minify action to compact, and the validate action to check syntax. All processing runs in your browser.

What this tool does

The JSON formatter parses standard JSON and serializes it again with consistent indentation. It shows the root data type, the number of keys at the top level, and the total input size. It does not modify the JSON structure — it only changes whitespace.

Supported input

Valid standard JSON. This means:

• Object keys must be double-quoted
• String values must use double quotes
• No trailing commas
• No comments (standard JSON does not allow them)
• No single quotes
• No unquoted keys

JavaScript object literal syntax is not valid JSON and will be rejected by the validator.

Output

• Formatted: JSON with two-space indentation
• Minified: JSON with all unnecessary whitespace removed
• Validation result: passes or shows the character position of the syntax error

Step-by-step use

1. Paste JSON into the input area — an API response, a config snippet, a log entry, or any JSON document
2. The tool validates the syntax automatically
3. If valid, formatted output appears in the output area
4. Use the minify button to produce compact output
5. Use the copy button next to either output to copy it to your clipboard

Data handling and processing behavior

The formatting action is designed to happen in your browser using the browser's built-in JSON parser. The JSON is parsed into a JavaScript value in memory, then serialized back to a string. Avoid entering sensitive data unless you have reviewed the current public implementation.

Large JSON documents (multiple megabytes) hold the entire text in browser memory. On older or memory-constrained devices, this may cause the tab to slow down.

Limits

• Standard JSON only. JSON with comments (JSONC), JSON5, or JavaScript object literal syntax is not supported.
• No size limit enforced by the tool, but very large files may slow the browser.
• The tool does not preserve key order or value precision for extremely large numbers.

Common errors

Paste error: "Unexpected token"

This usually means the input is not valid JSON. Common causes:

• Single quotes instead of double quotes around strings
• Trailing comma after the last item in an array or object
• Unquoted object keys
• A comment line (// or /* */)

Fix the source JSON before pasting, or use a JSON-to-JSON converter to clean up non-standard syntax.

Paste error: "Unexpected end of JSON input"

The input was truncated. Either the paste was incomplete or the source had encoding issues. Re-copy the full JSON from the source and paste again.

Next steps

• CSV to JSON Converter — convert spreadsheet exports to JSON before formatting
• JSON Path Extractor — extract specific values from a large JSON document after formatting
• JSON to YAML Converter — convert formatted JSON to YAML for config file workflows
• XML Formatter — format XML responses from REST APIs