JSON Swiss

JSON Swiss

JSON Validator

JSON Input

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Validation Results

Start validating JSON

Enter JSON to see validation results

Why Use JSONSwiss’s JSON Validator?

  1. 1

    Find syntax errors with line and column details in the editor.

  2. 2

    Use available quick fixes for common commas, quotes, and comment problems.

  3. 3

    Review validation warnings, statistics, and a downloadable report without uploading JSON.

JSON Validator is for checking whether a document is valid JSON before it becomes an API request, a fixture, a configuration file, or an export. It shows both parse errors and the practical details needed to find the broken character without manually scanning a long payload.

Validate JSON Online

JSON Validator parses the JSON you paste or import and reports syntax errors where they occur. The validation runs locally in the browser, so you can check a working payload while keeping the source available for editing and review.

A successful validation means the document follows JSON syntax; it does not prove that every business value is correct for a particular API or schema. Use the result as a reliable syntax gate, then apply the domain-specific checks your workflow needs.

JSON Syntax Checker

The JSON Validator syntax checker identifies the line and column associated with a parser error, helping you jump to a missing delimiter, quote, bracket, or malformed value. That is more useful than a generic “invalid JSON” message when a nested document has hundreds of lines.

Available quick fixes can help with supported common mistakes while preserving the original editing context. Review each proposed fix, especially when an error occurs inside a string or a nested array where a small edit may change the intended structure.

Common JSON Syntax Errors

JSON commonly fails because of missing or trailing commas, single quotes, comments, unquoted keys, or unmatched brackets. JSON Validator points to the syntax location so you can decide whether the issue is a simple typo or a sign that the source was copied, truncated, or assembled incorrectly.

It also surfaces warnings for deeply nested data and unsafe integer values. These warnings do not necessarily make JSON invalid, but they can matter when a downstream language, database, or API handles the value with different limits or precision.

JSON Validator Warnings and Reports

Beyond the parser result, JSON Validator provides statistics and a downloadable report that can support a bug ticket, handoff, or review. The report is helpful when you need to give another developer a repeatable record of the input issue rather than only a screenshot of an error message.

Treat warnings as a prompt for closer review, not as automatic proof of bad data. A deeply nested structure may be valid for your application, while an unsafe integer may need a string representation or another explicit decision in the system that consumes it.

JSON Validator Examples

Reference demo

Locate a missing comma

This document is missing the comma after the name property. JSON Validator points you to the error location so the fix is easy to review.

Invalid JSON
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{
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"name": "Maya"
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"role": "admin"
4
}
Validator result
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Syntax error
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Line 3, Column 3
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Missing comma after "name" value

Use the line and column details to find the issue, then apply a supported quick fix or edit the JSON directly.

Reference demo

Apply a supported trailing-comma quick fix

A trailing comma is invalid JSON. When the validator offers a matching quick fix, you can review the single edit before accepting it.

Invalid JSON
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{
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"name": "Maya",
3
"role": "admin",
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}
Quick-fix result
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{
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"name": "Maya",
3
"role": "admin"
4
}

Quick fixes are available for supported diagnostic patterns; inspect the proposed edit when the input contains nested values or strings.

Reference demo

Confirm a valid API payload

A successful validation gives you a clear syntax gate before you format, compare, or send a payload to another system.

JSON input
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{
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"id": "ord_204",
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"paid": true,
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"items": [1, 2]
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}
Validator result
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Valid JSON
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No syntax errors found

A valid result confirms JSON syntax, not business rules or conformance with a separate schema.

JSON Validator vs JSON Repair

JSON Validator identifies what is wrong; JSON Repair attempts to correct malformed syntax. Choose validation when you want a precise diagnosis and repair when the payload needs a recovery attempt before it can be checked normally.

When the document needs automatic correction, repair invalid JSON first, then return to JSON Validator to confirm the result and review the affected fields.

How to Validate JSON

  1. 1Paste or import the JSON you need to check in JSON Validator.
  2. 2Review line and column diagnostics, warnings, and any supported quick fixes.
  3. 3Export the report, beautify valid JSON, or compare valid payloads when validation is complete.

Once the document is valid, use the Formatter to beautify valid JSON or JSON Compare to compare valid payloads.

Related JSON Tools

Frequently Asked Questions

What does the JSON Validator check?

The validator checks whether JSON parses correctly, reports syntax diagnostics with line and column details, and shows validation statistics and available warnings.

What JSON errors can it find?

It can identify common syntax issues such as missing or trailing commas, unmatched brackets, malformed strings, invalid escapes, single quotes, comments, and unquoted keys. Supported quick fixes help with several common cases.

What is the difference between an error and a warning?

An error means the JSON cannot be parsed. A warning means it may parse but has a potentially risky pattern, such as deep nesting or an integer that cannot be represented safely in JavaScript.

What is included in the validation report?

The downloadable report includes validation status, errors, warnings, and statistics such as object count, array count, maximum depth, key count, and character count.

What is the difference between JSON validation and JSON repair?

Validation tells you what is wrong and where. Repair attempts to correct common malformed syntax. Validate first when you need diagnostics; use Repair when the input needs automatic correction.

Can I validate large JSON files?

Typical API responses, config files, and log snapshots can be checked locally. Very large inputs may take longer to analyze because the work happens in your browser.

Is JSON validation processed locally?

Yes. Validation, diagnostics, quick fixes, statistics, and report generation run locally in your browser.