Format, validate, minify, and repair JSON payloads directly in your browser. This tool parses raw JSON strings, highlights syntax errors with exact line and column numbers, applies 2-space indentation or minification, and performs best-effort repairs for common malformed syntax like trailing commas or single quotes. All processing runs locally in your browser.
Minified JSON payloads returned by APIs or loggers condense data onto a single line, making complex objects difficult to inspect. Formatting parses the raw JSON string and serializes it with line breaks and consistent 2-space indentation.
Before formatting:
{"user":{"id":101,"name":"Alice","roles":["admin","dev"]}}After formatting:
{
"user": {
"id": 101,
"name": "Alice",
"roles": [
"admin",
"dev"
]
}
}The editor validates JSON on every change using strict JSON.parse() syntax rules. When syntax errors occur, a red Invalid Syntax indicator displays the exact line and column position where parsing failed.
When errors are detected, the Fix JSON action becomes available. It applies a series of best-effort regex heuristics to repair common malformed patterns before re-validating:
Fix JSON button to strip comments and normalize keys into strict JSON.Formatting and minification both produce valid JSON with identical parsed data structures, but serve different purposes:
While minification reduces raw string character count, HTTP compression algorithms (such as gzip or Brotli) already compress repetitive whitespace efficiently over the wire. Minification is most useful for inline configuration files, environment variables, or localStorage items. If your JSON originates from a decoded JWT payload, inspect it with our JWT Decoder.
JSON.stringify(). As a result, the tool preserves parsed data values, but normalizes textual representation. Unicode escape sequences (e.g., \u00A9) are decoded to their corresponding characters, and non-significant spacing within raw input is replaced by standard 2-space indentation. If your input is Base64-encoded, decode it first with our Base64 Decoder.When valid JSON is parsed, the tool calculates structural metrics to give you quick visibility into payload complexity:
If you need to format or minify JSON inside your codebase, use standard runtime serialization methods:
JSON.stringify(data, null, 2) produces 2-space indented output. Omit the third argument to minify.json.dumps(data, indent=2) formats JSON with 2-space indentation using the built-in json module.python -m json.tool input.json to format JSON directly in your terminal.For tabular datasets originally in CSV format, convert them using our CSV to JSON Converter.
Paste your raw JSON string into the editor under the `Source.json` tab, or click `Load Sample` to populate a demo payload.
The header badge displays `Valid` when syntax is correct. If invalid, the badge shows `Invalid Syntax` along with the line and column position of the error.
If syntax errors exist, click `Fix JSON` in the bottom toolbar to repair trailing commas, single quotes, unquoted keys, or comments automatically.
Click `Format` to pretty print your JSON with 2-space indentation, or click `Minify` to condense it onto a single line.
Switch to the `Output.json` tab to view the formatted result. Check the stats bar for payload size, total key count, and nesting depth. Toggle `Wrap` if viewing long minified lines.
Click `Copy Output` to copy the processed JSON to your clipboard, or `Download JSON` to export it as a `formatted.json` file.
Copy & paste production-ready code snippets for JSON Formatter & Validator in your language of choice
import json
def format_json(raw_json_str):
parsed = json.loads(raw_json_str)
return json.dumps(parsed, indent=4)
raw = '{"name":"John","age":30,"city":"New York"}'
print(format_json(raw))Master this tool with our expert tutorials and best practices.