Valid JSON object
Input
{"ready":true}Example output
{
"ready": true
}JSON Validator
JSON & Data100% Client-SideReady
JSON
0 lines0 chars
0 B / 4.77 MB
Read-only
0 lines0 chars
0 B
About this tool, examples & FAQ
Decide whether pasted text parses as JSON, entirely in your browser. Valid input returns structure diagnostics; invalid input returns an actionable error with line and column when the parser message provides a location. Syntax checking does not validate against a JSON Schema and says nothing about business correctness.
Key facts
| Accepted input | JSON text: objects, arrays, strings, numbers, booleans, or null |
|---|---|
| Validation output | Status, root type, and key or item counts, with optional 2-space formatting of valid JSON |
| Schema validation | Not supported: syntax checking only, no JSON Schema validation |
| Max input size | 5 MB |
| Execution deadline | 2 s |
| Processing location | Browser-only: pasted input is not uploaded |
How to use
- Paste your JSON snippet into the editor.
- Keep 'Format Validated Output' enabled for readable output, or turn it off to echo the input text unchanged.
- Click 'Run' to check the syntax.
- Inspect the structure diagnostics (validation status, root type, key count, item count) in the right panel.
- If errors exist, read the reported message and the line and column indicators when provided to locate the syntax violation, fix it, and run again.
- Use 'Copy' or 'Download' to retrieve the validated output.
Examples
Invalid JSON with trailing comma
Input
{"ready":true,}Example error
Expected double-quoted property name in JSON at position 14 (line 1 column 15)Edge cases
Root primitives
Top-level strings, numbers, booleans, and null are valid JSON texts and validate successfully, not just objects and arrays.
Duplicate keys
Duplicate object keys are not reported: the last value wins during parsing, matching JSON.parse behavior.
Number precision
Values follow standard JavaScript JSON precision: integers beyond 2^53 - 1 may lose least-significant digits, and out-of-range literals such as 1e999 do not survive the round trip.
Syntax is not trust
A 'Valid JSON' result means the text parses. It does not mean the data matches any schema, is safe to execute, or is correct for your application.
How it works
- Rejects empty or whitespace-only input before parsing.
- Parses the input with the platform JSON parser and converts engine diagnostics into line and column indicators.
- Reports structure diagnostics: validation status, root type, and key or item counts.
- Returns valid JSON formatted with 2-space indentation when the option is enabled, otherwise echoes the input text.
- Executes inside a Web Worker bounded by the tool deadline.
Related workflows
JSON Formatter
Prettify, indent, and format JSON strings with customizable indentation and key sorting.
JSON Minifier
Compress and minify JSON data by stripping whitespace and indentation while preserving string values.
JSON ↔ YAML Converter
Convert bi-directionally between JSON and YAML with strict alias and cycle protection, custom indentation, and swap support.
JSON ↔ CSV Converter
Convert bi-directionally between JSON arrays of objects and tabular CSV/TSV data with delimiter options, header validation, and spreadsheet formula injection protection.
Frequently asked questions
Can I use single quotes for strings?
No. JSON strings must use double quotes. Single-quoted text such as {'ready':true} is invalid JSON and fails validation.
Are trailing commas allowed?
No. A comma after the last property or element, as in {"ready":true,}, is a syntax error. Remove the trailing comma and run again.
Can JSON contain comments?
No. The JSON format has no comment syntax, so single-line and multi-line comments are rejected. Strip comments before validating.
What does a missing brace error mean?
Every opening brace or bracket needs its matching closer. The reported line and column point to where parsing stopped, which is usually at or just after the unclosed structure.
Does the validator check my data against a JSON Schema?
No. This tool only decides whether the syntax parses. It never checks required fields, value types, or any other schema rule.
Is my pasted input uploaded anywhere?
No. Validation runs inside an isolated Web Worker in your browser, and pasted input is not uploaded for processing. The browser still requests site assets from the host; clipboard, downloads, and analytics are separate boundaries.
References
- RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format — JSON syntax, values, and data model