JSON Tools
JSON Validator
Check whether text is valid JSON and locate syntax mistakes before a request, deployment, or import fails. The validator reports a line and column when the browser parser can identify the error position.
✓ Every tool runs in your browser. We do not upload your input or output.
Keyboard shortcuts
Ctrl/⌘ + Enter: process
Ctrl/⌘ + Shift + F: full screen
Esc: exit full screen
Ctrl/⌘ + F in editor: search
How to use
- Paste JSON into the editor, upload a file, or load the sample.
- Wait for automatic validation after typing or press Ctrl or Command plus Enter to check immediately.
- Look for Valid JSON in the result, or read the error message and highlighted line number.
- Activate the error message to move the cursor to the reported column, then correct the input and validate again.
Examples
Catch a trailing comma
JSON does not permit a comma after the final property in an object.
{"enabled":true,}Unexpected token near the closing brace
Check an API fixture
The object parses successfully and is ready to use as a JSON fixture.
{"items":[1,2,3],"count":3}Valid JSON
Syntax checks before deeper checks
JSON syntax is strict. Property names need double quotes, strings need double quotes, and trailing commas are not allowed. A document must contain one complete JSON value, such as an object, array, number, string, boolean, or null. The validator helps you catch these structural problems early, before application code tries to consume the data.
This tool is especially useful for checking copied API examples, edited test fixtures, and configuration files assembled from templates. If a large document fails, start at the reported location and inspect the preceding field as well. Parsers sometimes report the point where they can no longer continue, which can be just after the actual typo.
What a successful check means
A successful result means the text can be parsed as JSON. It does not verify an API contract, JSON Schema, business rule, or referenced identifier. After syntax passes, run your application’s schema or integration tests for those checks. To make a valid document easier to inspect, open it in the JSON Formatter or Viewer.
For example, {"count":"three"} is valid JSON, but a service expecting a numeric count may reject it. Likewise, a response can parse while omitting a required items array. Use this validator to remove syntax errors from the investigation, then compare the parsed shape with the receiving application’s contract. If the source intentionally allows comments or trailing commas, confirm its format before treating it as standard JSON.
Frequently asked questions
What rules does the validator use?
It uses the browser JSON parser, so the input must follow standard JSON syntax rather than JavaScript object literal syntax.
Why are comments rejected?
Standard JSON has no comment syntax. Remove comments or use a format designed for annotated configuration.
Can it check a file without uploading it?
Yes. File selection reads the file locally in the browser and does not send its contents to a server.
Does valid JSON mean my schema is correct?
No. It confirms syntax only. A valid object can still omit required fields or contain values your application does not accept.