JSON Formatter & Validator Online — Pretty Print or Minify JSON Free
Format, validate, and minify JSON data with syntax highlighting.
Privacy first: This tool runs entirely in your browser. Your data never leaves your device.
Format unreadable or minified JSON into a clean, indented structure, or minify formatted JSON into a compact single line. The tool validates your JSON and highlights any syntax errors. All processing runs locally in your browser — no data is sent to a server.
How to Use JSON Formatter
- Paste your JSON: Paste raw or minified JSON into the input area.
- Format or minify: Click "Format" to pretty-print the JSON with indentation, or "Minify" to remove all whitespace.
- Review validation results: If the JSON contains syntax errors, they are highlighted with the line number and error description.
- Copy the output: Click "Copy" to copy the formatted or minified result to your clipboard.
Features
- Pretty-prints JSON with configurable indentation
- Minifies JSON to a single compact line
- Validates JSON and reports syntax errors with line numbers
- Syntax highlighting for readability
- Runs entirely in your browser — no server upload
- Free with no account required
Common Use Cases
JSON formatting is an everyday task for developers debugging API responses, reading configuration files, and preparing data for documentation. Minification is used to reduce payload size in production API responses.
Frequently Asked Questions
- Can the formatter detect JSON errors?
- Yes. The validator highlights syntax errors and shows the line and character position of each error.
- What indentation is used for formatting?
- The default is 2-space indentation. You may be able to change this to 4 spaces or tabs in the settings.
- Is there a size limit on the JSON I can format?
- There is no enforced limit. Very large JSON files may be slower to process, but typical API responses and config files are handled instantly.
- Does it support JSON5 or JSONC (with comments)?
- The tool targets standard JSON (RFC 8259). JSON5 and JSONC with comments are not officially supported.