Why You Need a JSON Validator
Ever spent 20 minutes debugging an API call only to realize there was a stray comma in your JSON payload? Yeah, we've all been there. A validator catches those mistakes in literally one second. Paste your JSON, hit validate, and you either get a green checkmark or a clear error message telling you exactly what's wrong and where.
This is especially handy when you're working with config files. One misplaced bracket in a tsconfig.json or package.json can break your entire build and the error message from your build tool might not even point to the right line. Our validator shows you the exact position of the syntax error.
Common JSON Syntax Errors
Most JSON errors fall into a handful of categories. Trailing commas are the number one culprit — JavaScript allows them but JSON doesn't. Single-quoted strings trip up developers who switch between JS and JSON. Unquoted keys are another one — valid in JavaScript objects but invalid in JSON. This tool catches all of these and tells you exactly what to fix.
Trailing Commas
This is probably the most common mistake. You copy-paste a JavaScript object, and it has a trailing comma after the last property. JavaScript doesn't care, butJSON.parse() throws an error. Our validator shows you exactly where the trailing comma is so you can remove it.
Single vs Double Quotes
JSON requires double quotes for strings. If you're coming from Python where single quotes are normal, or from YAML where quotes are often optional, this catches you. The validator will point to the exact position where it expected a double quote.
JSON Lint vs JSON Validate
People use these terms interchangeably, but there's a subtle difference. Validation checks if your JSON is syntactically correct — proper brackets, quoted keys, valid values. Linting goes a step further and warns you about things that are technically valid but probably wrong, like duplicate keys or suspiciously deep nesting.
Our tool does both. It'll catch hard errors like missing commas, but it'll also give you stats about your data — number of keys, nesting depth, file size — so you can quickly assess what you're working with before sending it to an API.
Debugging API Payloads
The most practical use case is debugging API requests. You've built a 50-line JSON body for a POST request, and the API returns a 400 Bad Request. Is it the JSON syntax? Is it the data? Start by validating the JSON here. If it's valid, the problem is in the data itself, not the format — and you've saved yourself from chasing the wrong bug.