JSON Validator Online Free and Instant
Overview
A single malformed character can break your entire JSON payload. The validator checks every token, bracket pair, and string escape against the JSON spec (RFC 8259) and reports errors with the exact line number and a plain-language description. Zero uploads, zero sign-up.
How to Use This Tool
Paste your JSON and click Validate. Green output means your JSON is syntactically correct. Red output shows the first error with its line number, the problematic token, and a suggestion for the fix.
Ready to get started? It's free, no registration required, and your files never leave your device.
PDF Tool →Frequently Asked Questions
What standard does this JSON validator follow?
The validator follows RFC 8259, the current JSON specification. This covers valid UTF-8 encoding, proper string escaping, number formats, and the exact rules for allowed whitespace.
Can I validate JSON from a .json file?
Yes. You can paste the file contents or use the file upload button. The validator accepts .json, .txt, and any plain text format containing JSON.
What is the difference between valid JSON and valid JavaScript object literal?
JavaScript object literals allow single quotes, unquoted keys, trailing commas, and comments. Valid JSON requires double quotes on all keys and strings, no trailing commas, and no comments.