JSON Validator
Check JSON syntax quickly and surface readable parse errors before you ship or debug.
What is JSON Validator?
JSON Validator focuses on fast pass or fail feedback so malformed payloads are easier to diagnose before they reach downstream systems.
Use it when a request body is rejected before your endpoint runs, a configuration fails to load, or a copied response may be truncated. Check syntax before investigating the payload's meaning.
How to use JSON Validator?
Step 1
Try the included example input, then replace it with a redacted sample from the system you are debugging.
Step 2
Paste the raw JSON payload.
Step 3
Run validation to see whether the document parses cleanly.
Step 4
Use format if you want a readable view after validation passes.
Example input / output
The payload {"active":true,} fails because of the trailing comma. Removing it produces {"active":true}, which is syntactically valid but still needs your API contract checks.
Review the result for completeness before copying it into code, a test, a ticket or another tool.
Example input
{"requestId":"abc-123","success":true,"items":[1,2,3]}Check the result
- JSON does not allow comments or dangling commas.
- Copied payloads from logs often contain escaped wrappers or truncation.
Practical developer examples
Separate malformed JSON from an API validation error
First check that the exact request body parses. If it does, investigate required fields, types and allowed values with JSON Schema or the server's validation response.
Check a copied configuration
Look for single-quoted strings, comments and trailing commas. These may be accepted in JavaScript or JSON5 but are not accepted by this strict JSON parser.
Common developer use cases
A successful syntax check rules out a parsing failure; it does not prove the payload is safe, complete or valid for a particular endpoint.
Common issues
FAQ
Does this validator check JSON Schema?
No. This page checks JSON syntax. Use JSON Schema Validator & Generator to check required properties and types against a schema, then test business rules in your service.
Are comments, single quotes and trailing commas valid JSON?
No. JSON requires double quotes around property names and strings, and accepts neither comments nor trailing commas. Boolean values and null must be lowercase.
Can an array, string or null be valid JSON?
Yes. JSON can contain an object, array, string, number, boolean or null at the top level. Your API may impose a narrower requirement, such as an object with specific fields.
Does a valid result rule out duplicate keys?
No. This validator uses JSON.parse, which accepts duplicate object keys and keeps the last value. It is a syntax check, not a duplicate-key or numeric-precision audit.