JSON Beautifier & ValidatorFormat, minify, and verify payloads without leaving your browser
Paste raw API payloads, log fragments, or minified config blobs into a browser-local workspace. OpsecForge parses them client-side with native JSON APIs and does not send the pasted payload to a tool-processing backend. The page itself still loads site resources and aggregate analytics.
Use beautify to normalize spacing with native stringification, or minify to compress the same JSON into a single line. Invalid payloads surface an immediate parser error.
Errors the parser reports, and the fix
The tool validates with the browser's own JSON.parse, so it accepts exactly what that parser accepts. JSON is stricter than JavaScript object syntax. Each row below is an input you can paste to see the error; the message shown is what Chrome and Node.js (V8) print, and Firefox and Safari word theirs differently. The position counts characters from the start of the input.
| Mistake | Input | Message (V8) | Fix |
|---|---|---|---|
| Trailing comma | {"a":1,} | Expected double-quoted property name in JSON at position 7 (line 1 column 8) | Remove the comma after the last member. |
| Single quotes | {'a':1} | Expected property name or '}' in JSON at position 1 (line 1 column 2) | Use double quotes around keys and strings. |
| Unquoted key | {a:1} | Expected property name or '}' in JSON at position 1 (line 1 column 2) | Quote the key: "a". |
| Comment | {"a":1 // note } | Expected ',' or '}' after property value in JSON at position 7 (line 1 column 8) | JSON has no comments; delete them. |
| NaN | {"a":NaN} | Unexpected token 'N', "{"a":NaN}" is not valid JSON | NaN, Infinity and undefined do not exist in JSON; use null or a string. |
| Leading zero | {"a":01} | Unexpected number in JSON at position 6 (line 1 column 7) | Numbers cannot start with 0 unless the value is 0 or 0.x. |
What formatting can change
Beautify and Minify parse the text and write it back, so the output reflects how JavaScript reads the document, not a character-for-character copy. Numbers are the main surprise: they become IEEE 754 doubles, which hold integers exactly only up to 253 − 1 (9007199254740991). RFC 8259 warns that numbers beyond that range may not interoperate. Try this input in Minify:
{"id":12345678901234567890,"price":10.50,"exp":1e2}{"id":12345678901234567000,"price":10.5,"exp":100}The 20-digit id is rounded, 10.50 loses its trailing zero and 1e2 is written as 100. When an integer in your input is outside the safe range, the tool shows a precision warning under the toolbar. If exact digits matter (database ids, snowflake ids), have the producer send them as strings. Duplicate keys are not an error: Minify turns {"a":1,"a":2} into {"a":2} because the last value wins, although RFC 8259 says names SHOULD be unique.
The same job on the command line
echo '{"a":1,"b":[2,3]}' | jq . # 2-space indent
echo '{"a":1,"b":[2,3]}' | python3 -m json.tool # 4-space indent by default
python3 -m json.tool --indent 2 data.jsonJSON.stringify(JSON.parse(text), null, 2) // beautify
JSON.stringify(JSON.parse(text)) // minifyUnlike this page, jq 1.7.1 and Python's json.tool print 12345678901234567890 back unchanged, so use one of them when you need to reformat a document without touching its numbers.
- Does key order change?
- Mostly no. Keys keep their input order, with one exception: JavaScript objects list integer-like keys such as "1" first in ascending order, so {"b":1,"2":2,"1":4} is written back as {"1":4,"2":2,"b":1}.
- Is my JSON uploaded?
- Parsing runs in this tab with JSON.parse and the tool does not send the text to a processing backend.