Validate JSON and jump to the exact line and column of each error, locally in your browser.
FeedbackEnsure your JSON is RFC-compliant with our strict JSON Validator. It pinpoints syntax errors with line numbers and descriptive messages, helping you fix issues like missing commas, unclosed braces, or invalid types.
Paste the JSON you want to check into the input editor.
Click 'Validate' to run a strict parse of the document.
Read the result: valid confirmation or a precise error message.
Use the reported line number to jump to and fix the problem.
A single missing comma or unclosed brace can break an entire API call or config load. Validating early tells you exactly where the problem is so you can fix it before it ships.
Descriptive messages with line numbers point you straight to the broken token.
The validator follows JSON rules closely, catching trailing commas and invalid types.
Validation runs entirely in your browser, so sensitive payloads never leave your device.
A JSON validator answers one question: will a parser accept this document. That sounds narrow and it is the question that matters, because every consumer downstream of you, in every language, applies the same grammar. If it parses here it parses there.
The useful part is not the yes or no but the location. Modern JavaScript engines changed how they report syntax errors: instead of a character offset, newer browsers return a quoted window of the source around the problem. That is friendlier to read and considerably harder for a tool to turn into a cursor position, which is why some validators regressed to simply saying "unexpected token" with no line at all. We locate the failure by bisection, narrowing the document until the smallest failing fragment is found, so the error still points at a line and column you can act on.
Most real failures come from a small set of causes, and recognising them saves the search. Trailing commas after the last element of an object or array are legal in JavaScript and illegal in JSON. Single quotes around strings are likewise a JavaScript habit that JSON rejects. Unquoted object keys are valid in JavaScript object literals and not in JSON. Comments of either kind are not part of the format, however reasonable that seems in a configuration file. And a bare NaN or Infinity, which JavaScript will happily produce, has no JSON representation at all.
Encoding produces the confusing failures. A byte order mark at the start of a file is invisible in most editors and makes the first character not the opening brace the parser expects. Text pasted from a word processor can carry curly quotation marks that look almost identical to straight ones and are not the same character. A document that looks perfect and refuses to parse at position zero is almost always one of these two.
Validity is not correctness. A document can parse cleanly and still be wrong for its purpose: a required field missing, a number where a string was expected, an array where the consumer wanted an object. That is schema validation, a separate and heavier question, and a validator that only checks grammar will tell you nothing about it. Knowing which of the two you actually need saves time.
As with every tool here, the document is parsed in your browser and never transmitted. That is worth caring about precisely because the documents people validate are the ones that are failing in production, and those tend to be full of real identifiers belonging to real users.
Format, validate and minify JSON in your browser. Paste, prettify, copy: nothing is uploaded.
Explore large JSON as a collapsible tree in your browser. Search keys and values; nothing is uploaded.
See the differences between two JSON documents side by side, computed locally in your browser.
The same tool answers on HTTP. Free, 1,000 calls a day, no card, and one token works across every Astral API.
POST https://astraljson.com/api/v1/json-validator