Validate any JSON string against RFC 8259. Pinpoints missing brackets, trailing commas, unquoted keys, and type errors with line-level error reporting. No server contact required.
Key Features
Strict compliance verification against the RFC 8259 specification
Exact line and column number reporting for syntax errors
Visual error highlighting directly within the code editor
Validates large datasets quickly using browser-native parsing
How to Use
Enter or paste your JSON code into the editor.
Click "Validate JSON" to check for syntax issues.
Review the status panel to see if the JSON is valid or read detailed error messages.
Click on any reported error to jump directly to the problematic line.
Example
Sample input
{"items":[1,2,3],"meta":{"version":1}}
Sample output
Valid JSON
Edge Cases
Trailing commas after last element
Single-quoted strings (invalid in strict JSON)
Unclosed brackets or braces
Frequently Asked Questions
What common syntax errors does the validator detect?
It detects trailing commas after the last item, single quotes used instead of double quotes, missing quotes around object keys, and unmatched brackets or braces.
Does the tool check JSON against a custom JSON Schema?
This tool checks strict structural syntax according to RFC 8259. It confirms whether the text is valid JSON that any compliant parser can read.
Is there a file size limit for validation?
Large files are processed on our server in memory. Very large payloads may hit request or timeout limits depending on size.
Privacy notice: when you run this tool, your input is sent over HTTPS to our server, processed in memory and returned. It is not stored or logged. Avoid pasting live secrets such as private keys or passwords.