Paste JSON to validate its syntax instantly. Get clear error messages showing the exact line and position of the problem, and catch common issues like trailing commas and single quotes before they break your code. Free, online, and 100% client-side.
100% client sideInstant resultNo data sent
Input JSON
Output
Paste JSON to format, beautify, validate, minify, analyze, or view it as a tree.
0 input chars0 output charsWaiting for valid JSON
Frequently asked questions
4 answers
The most common causes are trailing commas after the last item in an object or array, single quotes instead of double quotes around keys and strings, unquoted keys, and comments (JSON does not allow // or /* */ comments). Other frequent issues include missing commas between items, unescaped control characters inside strings, and values like undefined or NaN that JavaScript accepts but JSON does not.
When validation fails, the tool shows a clear, human-readable message describing what went wrong and where, including the line number and character position of the problem. Instead of a cryptic parser dump, you get something you can act on, such as an unexpected token at a specific location, so you can jump straight to the offending character and fix it.
JSON validation checks syntax: is the text well-formed JSON that a parser can read? JSON Schema validation checks structure and content: does the parsed data have the required fields, correct types, and allowed values defined by a schema? This page handles syntax validation. If you need to validate data against a schema, use our JSON Schema Validator at /tools/json-schema-validator.
No. Validation runs entirely in your browser with client-side JavaScript. Nothing you paste is uploaded, stored, or sent to any server, and the tool keeps working even if you go offline after the page loads. That makes it safe for validating JSON that contains credentials, personal data, or proprietary payloads.
A single misplaced comma can take down a deployment, and default parser errors rarely tell you where the problem is. This free online JSON validator acts as a JSON lint and syntax checker in one: paste any JSON and it is parsed instantly, with failures reported as clear messages that point to the exact line and character position. It catches the classics (trailing commas, single quotes, unquoted keys, comments) that trip up copy-pasted JavaScript object literals and hand-edited config files. When your JSON passes, you also get a beautified version and a tree view for inspection. Everything runs client-side, so validating API responses, environment configs, and data exports never exposes your data to a server.