Catching a trailing comma
A config that a program rejects turns out to have a comma after the last item; the validator points straight at the line.
Use JSON Validator
Converts json to result in this tab, with nothing sent anywhere.
Runs entirely on your deviceThe conversion happens in this browser tab. Nothing you type is uploaded, logged or stored, which is worth knowing for anything you would not paste into a search box.
Explore developer and data tools
Find related browser-local tools for nearby tasks without starting another search.
Browse all developer and data toolsAbout JSON Validator
A JSON validator answers the one question that stops everything else: is this text actually valid JSON? A single trailing comma, an unquoted key or a missing brace makes a whole config file, API response or export unparseable, and the error a program throws is often cryptic about where. This tool parses the JSON in your browser and tells you plainly whether it is valid - and if not, it points at the line and column where parsing broke, so you can fix the exact character rather than hunting through the whole document. Because it runs entirely on your device, you can safely check a config file or an API payload that contains keys and tokens you would never paste into a random website.
Using JSON Validator
- Paste your JSON. It is parsed in this browser tab the moment you type - nothing is sent anywhere.
- If it is valid, the tool confirms it and describes the top-level shape, such as an object with a certain number of keys or an array of items.
- If it is invalid, the message names the line and column where parsing failed and what the parser expected, so the fix is a precise edit.
Where json validator helps
Checking an API response
Paste a response body to confirm it is well-formed JSON before writing code that depends on parsing it.
Before you use the result
- It checks syntax, not meaning: valid JSON can still have the wrong keys or values for your schema. Use a JSON Schema validator for that deeper check.
- The parser reports the first error it hits. A file with several problems is fixed one message at a time, re-checking after each.
- Validation has no reverse - there is no 'un-validating' a document - so unlike the converters here this tool is one-way by nature.
Questions about JSON Validator
Why is my JSON invalid?
Common causes are trailing commas, single quotes instead of double, unquoted keys, or a missing bracket. The tool names the line and column so you can see which.
Does it check my data is correct?
No - only that the syntax is valid JSON. Whether the keys and values match what your program expects is a separate, schema-level question.
Related tools
JSON Unescape and Escape
Unescape JSON strings or create valid JSON escapes locally. Remove one encoded string layer, handle Unicode safely, and reject malformed sequences.
JSON Diff
Compare two JSON documents by structure and value. Find added, removed, changed, and type-changed paths locally in your browser.
JSON Formatter and Validator
Format, minify, and validate JSON locally in your browser. Inspect keys, values, nesting depth, and root type without sending private API data to a server.
YAML Validator
YAML Validator in your browser. Instant, accurate, and nothing is uploaded.
XML Validator
XML Validator in your browser. Instant, accurate, and nothing is uploaded.
CSV Validator
CSV Validator in your browser. Instant, accurate, and nothing is uploaded.
Base64 Validator
Base64 Validator in your browser. Instant, accurate, and nothing is uploaded.