Overview
Paste JSON to get a clear valid/invalid verdict. When the browser’s parser can pinpoint where things broke, the error is translated from a raw character offset into a line and column number you can jump straight to - useful when a config file or API response fails to parse and you need to find the problem fast without scanning the whole thing by eye. Not every parse error carries a precise position (some, like an abruptly truncated input, only report that something’s wrong, not exactly where), so this tool always shows the browser’s full error message either way rather than a bare "invalid" verdict. Valid input also gets a quick structural breakdown: root type, top-level item count, maximum nesting depth, and total value count, so you can sanity-check the shape of a response before working with it further. This is a validation-only tool - it checks syntax and reports where it broke, but doesn’t reformat, pretty-print, or minify. For that, use the JSON Formatter, which shares the same underlying parser but focuses on producing clean, indented output instead of diagnosing errors. Runs entirely client-side; nothing you paste is ever uploaded.
Best for: Finding exactly where a config file or API response broke JSON syntax
How to use this tool
- Paste your JSON. Drop in a config file, API response, or any JSON string you need to check.
- Instant syntax check. The parser validates as you type and reports a pass/fail verdict immediately.
- Exact error location. On failure, the raw parser position is translated into a line and column number you can jump straight to.
- Structure breakdown on success. Valid JSON gets a summary of its root type, item count, nesting depth, and total values.
Why use this tool
Line and column, not just a position offset
Translates the parser’s raw character position into a line/column you can actually navigate to in an editor.
Structural sanity check
See nesting depth and item counts at a glance to confirm a response has the shape you expected.
Validation-focused, not formatting-focused
No indent options or output panel to work through - just a direct verdict, for when that’s all you need.
Nothing leaves your browser
Parsing happens entirely client-side, which matters when the JSON contains real API responses or config secrets.
Frequently asked questions
Both use the same underlying parser, but they’re built for different moments. The JSON Formatter is for when you already have valid-ish JSON and want clean, indented output or a minified version. This validator is for when JSON is failing to parse and you need to know why - it surfaces a line/column error location when the browser’s parser can determine one, a structural breakdown for valid input, and the full error message either way, instead of formatted output.
JSON parsers stop at the first syntax error they encounter, since everything after an unclosed brace or a missing comma is unparseable until that first issue is fixed. Fix the reported line and column and re-check - if there’s a second error further in, it’ll surface on the next pass.
Total values counts every individual value in the structure - each object, array, string, number, boolean, and null, including nested ones. Nesting depth is how many levels deep the most-nested value sits; a flat object with no arrays or nested objects has a depth of 0.