Reading minified or deeply nested JSON without formatting is genuinely hard — brackets and commas blur together, and a single misplaced comma can be invisible in a wall of unindented text. This tool solves that specific problem: paste JSON in, and it comes back parsed and re-indented at 4 spaces per level, with JSON.parse doing double duty as both the formatter and the validator — if your JSON is malformed, parsing fails and you get the browser's own parse error (which usually names the problem and its approximate position) instead of a formatted result.
What this tool is, specifically
It's a beautifier and validator — there's currently no separate minify mode that strips whitespace back out for production use (if you need that direction, the CSS Minifier tool on this site does the equivalent for stylesheets, and a build tool's JSON loader typically handles JSON minification in a production pipeline automatically). What you get here is consistent, readable indentation and a clear signal of whether your JSON is syntactically valid at all.
Reading the error message
Since validation is just JavaScript's native JSON.parse under the hood, an invalid document returns that engine's own error text — something like "Unexpected token } in JSON at position 45." That's genuinely useful (it tells you roughly where the parser gave up), but it's shown as text below the input, not as an inline highlight at that exact character inside your pasted document — for a long file, you may need to count characters or use your editor's search to pinpoint the exact spot the message refers to.
Common uses
- Prettifying a raw API response or
curl/Postman export to actually read the data structure - Validating a
package.json,.eslintrc, or similar config file before committing it - Confirming a deeply nested response matches what your frontend code expects
- Producing clean, consistently indented JSON for documentation or a technical write-up
FAQ
Does it support JSON with comments (JSONC)?
No — standard JSON doesn't allow comments, and this validator matches strict JSON.parse behavior. If your source has comments (common in .eslintrc, tsconfig.json, and similar config formats that technically use JSONC), strip them first or this will report them as a syntax error.
Is there a minify mode?
Not currently — this tool only beautifies (4-space indentation). For minifying JSON, a build tool's bundler/loader is typically the right place for that in a production pipeline.
Does it point to the exact error location visually?
Not with inline highlighting — the error message includes the position JavaScript's parser reports (when available), but you'll need to locate that character yourself in the input rather than seeing it highlighted directly.
Is my data uploaded to a server?
No. Parsing and formatting run entirely in your browser via native JSON.parse/JSON.stringify. Nothing is sent anywhere.