Paste any JSON, get clean formatted output, minified version, or validation report. 100% in your browser, your config, API responses, secrets never leave your device.
Three steps, runs entirely in your browser, even offline.
Paste raw, minified or messy JSON into the input panel. The tool handles any size, from one-line objects to multi-MB arrays.
Format: clean, indented output (2 spaces, 4 spaces, or tab). Minify: single-line stripped JSON. Validate: parse and report any syntax errors with line numbers.
Copy formatted output to clipboard with one click, or download as .json file. The result is ready to paste into your code, API request, or config file.
Everything you need from a JSON tool, without the privacy risk of uploading.
Indent and prettify JSON with 2 spaces, 4 spaces or tab indentation. Sorts objects predictably; nested arrays/objects clearly visible.
Strip whitespace and produce single-line minified JSON, typical 30-60% size reduction. Perfect for config payloads, embedded JSON, network requests.
Parse JSON and report exactly where syntax fails. 'Unexpected comma at position 142', go fix it without guessing. Reports object/array depth and item count for valid input.
Pasted JSON never leaves your browser. Critical for API keys, secrets, customer data, internal configs you'd never trust to a 'free online formatter' that uploads.
Handles JSON from 1 byte to ~50 MB instantly. Browser's native JSON.parse is faster than any upload+server roundtrip.
No account, no API key, no marketing email. Open the tool, paste, format, leave. Free forever.
Why developers reach for a JSON formatter daily, and what to look for in one.
Format for humans. Minify for machines. Same data, different audience.
{"a":1,}, invalid in strict JSON (valid in JavaScript objects). Unquoted keys: {a:1}, keys must be double-quoted strings. Single quotes: {'a':'b'}, JSON requires double quotes only. Comments: // ... not allowed in standard JSON (JSONC and JSON5 allow them, but spec JSON doesn't). Unescaped backslashes: \n in a literal string needs \\n. The validator catches all of these with position info.Trailing commas, unquoted keys, single quotes, the three classic JSON sins.
JSON often contains secrets. Process locally, always.
Strict JSON for APIs. JSONC for config files with comments. Different specs, different tools.
Quick answers about the tool
JSON.parse is highly optimised. For files over 50 MB you may notice a brief pause as the parser runs; try splitting if your laptop has limited RAM. .json file. jq or a JS library after formatting. ,]), unquoted keys ({a:1} should be {"a":1}), single quotes ('foo' should be "foo"), unescaped characters in strings. The validator reports the exact position so you can fix it. Try the Sample button to see a valid JSON example.