JSON Validator

What “Valid JSON” tells you

The input contains one syntactically complete JSON value. That may be an object, array, string, number, boolean, or null. Validation does not confirm that an email exists, an amount is correct, or an API accepts the fields. Those checks require your application rules or a JSON Schema validator.

Invalid JSON, corrections, and expected results

Trailing comma: {"name":"Nikunj",} fails. Remove the final comma: {"name":"Nikunj"} → Valid JSON.

Unquoted property: {age:28} fails. Use double quotes: {"age":28} → Valid JSON. Single quotes are not a substitute.

Missing closing bracket: {"skills":["HTML","CSS"] fails at the end. Add }: {"skills":["HTML","CSS"]} → Valid JSON.

Valid syntax, ambiguous data: {"role":"reader","role":"editor"} passes syntax checking with a duplicate-property notice. Keep just the intended property before sending it to an API.

Primitive root: false is valid JSON. False, undefined, and NaN are not.

How to Use This Tool

Paste the document or load the sample. Open file accepts a UTF-8 JSON or text file.
Click Validate JSON, or leave Auto-update enabled to check after typing.
If invalid, read the line and column, select Go to error, and correct the first reported issue.
If valid, inspect Tree or Code and review any duplicate-property notice before copying or downloading.

Common Use Cases

Checking a configuration file before saving

Finding a missing comma in an API request

Learning valid JSON syntax

Inspecting values in a nested payload

How to work through an error

Use Go to error to select the detected location. Check the character immediately before it too: a missing comma or quote can become visible only at the next token. Correct the first error, run the check again, and continue until the status is valid. The validator reports the first failure rather than guessing at repairs that could change your data.

Duplicate names and large numbers

Duplicate object names are reported separately from syntax errors, because software can handle them differently. Both entries are preserved here. Number text is also preserved exactly, including large integers and exponents; a receiving application can still impose its own number limits.

Editor limits and privacy

Parsing and file reading happen in your browser; this tool does not send JSON to ToolSprouts. Each document may contain up to 1,048,576 UTF-8 bytes (1 MiB), 50,000 values, and 100 nesting levels. For more than 2,000 values, open branches individually; children appear in groups of 100. An editor-limit message describes a size limit, not invalid JSON.

Practical walkthroughs

Format JSON without changing large numeric IDs — Make an API response readable while keeping the exact number text you received.

Fix JSON errors one correction at a time — Use the detected location to repair a document without guessing at changes to its data.

Compare API responses without losing IDs or type changes — Review a configuration or API change using exact numeric tokens and a path-by-path report, rather than a visual scan of two formatted documents.

Frequently Asked Questions

Can it automatically fix my JSON?

No. Repairs can change the intended data, so the tool explains the first syntax failure and leaves correction to you.

Why is JSON with a repeated key marked valid?

The grammar permits repeated names. The tool warns because downstream software may reject duplicates or keep only one value.

Can I validate JSON Lines or JavaScript objects?

Paste one JSON value at a time. Multiple separate JSON values, comments, JavaScript object syntax, and JSON5 features are not supported.