JSON Formatter is a fast, browser-based utility for developers, students, and data analysts who need to validate, pretty-print, or quickly inspect structured data. Paste your JSON and get instant feedback — no server involved, no account needed, no data leaves your machine.
✓ Valid JSON
{
"tool": "Small Web Apps",
"status": "ready"
}Yes — all processing happens locally in your browser. Nothing is sent to any server. You can verify this by inspecting network requests.
It handles most typical use cases well. Very large files (several MB) may be slow depending on your device's memory, but there is no hard limit imposed by the tool.
Yes. Switch the indent selector to 0 spaces and the output will be compact single-line JSON with no extra whitespace.
Formatting (pretty-printing) adds line breaks and indentation so JSON is easy to read. Minifying removes all unnecessary whitespace to produce the smallest possible payload — useful before sending data over a network.
No. This is a strict JSON parser, matching the official JSON specification. Trailing commas, comments, and unquoted keys (allowed in JSON5/JSONC) will be reported as syntax errors.
It means the parser found a character it didn't expect at a specific position — commonly a trailing comma, a missing closing brace/bracket, single quotes instead of double quotes, or an unescaped character inside a string.
Not directly — NDJSON is multiple JSON objects separated by newlines, which isn't valid as a single JSON document. Format each line individually, or convert it to a JSON array first by wrapping the lines in [ ] and adding commas.