JSON Validator
Validate and format your JSON. Check for syntax errors and view detailed error information. The result updates as you type — nothing is uploaded.
Convert to
1. Enter JSON
2. Validation result
Looks good! Your JSON is valid (object).
Formatted JSON
Validation at a glance
Instant validation
Syntax is checked as you type — there is no Run button.
Detailed errors
See the message and jump to the line that failed.
Auto format
Valid JSON is pretty-printed so you can copy or download it.
100% private
Validation stays in this tab. Nothing is uploaded.
Your JSON stays private
Validation runs locally in your browser. Payloads never leave this device.
About validating JSON in the browser
JSON Validator checks syntax as you type in a two-pane editor. Valid JSON is pretty-printed on the right; invalid JSON shows the parser message and line. There is no Run button. Sample / Clear / Load file / Format stay local. Nothing is uploaded. Use it before you paste into an API, a config, or JSON Formatter. Validation does not change the left editor until you Format.
This is not JSON Schema, not OpenAPI, and not a type checker. Trailing commas, single quotes, and unquoted keys fail because JSON is not JavaScript. JSON Compare diffs two documents. JSON Minifier compresses. JSON to TypeScript emits types from a valid example. Shared persist with other JSON tools may keep a draft in this browser — clear if the payload is confidential.
Related: JSON Formatter, JSON Compare, JSON Minifier, Fake JSON. YAML ↔ JSON if the source was YAML. Nothing here uploads to a linter SaaS.
How to use
Paste JSON
Paste or type your JSON in the editor on the left.
Validate
We validate it in real time as you type.
Review results
See errors or formatted JSON on the right.
Use output
Copy, download, or format the JSON in the editor.
Common JSON issues
Missing comma
{ "a": 1 "b": 2 }Trailing comma
{ "ok": true, }Unquoted keys
{ ok: true }Single quotes
{ 'ok': true }Invalid values
{ "ok": True }Related JSON tools
JSON Formatter
Pretty-print JSON with indentation, optional key sorting, and minify. The result updates as you type.
JSON Minifier
Remove whitespace from valid JSON. Type or paste below — the result updates as you type.
JSON Compare
Compare two JSON objects side by side and visualize the differences. Find added, removed, and modified values instantly.
YAML ↔ JSON Converter
Convert YAML documents to JSON, or JSON values to YAML. The result updates as you type.
JSON Validator FAQ
Paste JSON into JSON Validator. The result updates as you type — there is no Run button. Valid JSON is pretty-printed on the right; invalid JSON shows the error and line. Nothing is uploaded.
No. Checking the structure does not change the left editor. Use Format to pretty-print valid JSON into the editor, or open JSON Formatter / JSON Minifier to transform it.
No. Trailing commas and single quotes fail because JSON is not JavaScript. Use JSON to TypeScript for types from a valid example, and JSON Compare to diff two documents.