JSON Swiss

JSON Swiss

Validate JSON

JSON Input

1

Validation Results

Start validating JSON

Enter JSON data to see validation results

How to validate JSON online – step-by-step guide

Use this online JSON validator to check JSON syntax, structure, and data integrity with real-time errors, warnings, and statistics.

  1. Step 1 – Paste or import JSON into the validator

    • Paste JSON into the left editor, or use Import to load from a file, URL, or clipboard.
    • Validation runs as you type, similar to a live JSON linter.
    • Use real API responses, config files, or log snippets to catch issues early.

  2. Step 2 – Review validation results

    • Check the Errors list for parse issues such as missing commas, unclosed brackets, or invalid escape sequences.
    • Review Warnings for deep nesting, unusually large strings, or suspicious patterns.
    • Use Statistics to understand object/array counts, maximum depth, and overall size.

  3. Step 3 – Fix errors and re‑validate

    • Click an error or warning to jump to the exact line and column.
    • Typical fixes: add missing commas, close braces/brackets, escape special characters, or remove trailing commas.
    • If the JSON is badly broken, open it in Repair JSON to auto-fix common syntax issues.

  4. Step 4 – Export a validation report

    • Click Report to download a JSON report with all errors, warnings, and statistics.
    • Share the report with your team for debugging, code reviews, or API contract checks.
    • The report includes line numbers, messages, and high-level recommendations.

Quick tips for beginners

  • Most invalid JSON comes from missing commas, trailing commas, or using single quotes instead of double quotes.
  • If you see a JSON parse error, start with the line and column shown in the message.
  • Validate JSON before sending it to APIs or saving it to a database to avoid runtime errors and broken payloads.
Example: JSON validation errors in an online JSON validator
// Invalid JSON (missing comma)
{
  "name": "Maeve"
  "age": 28
}

// Error: Expected ',' or '}' at line 3, column 3

// Valid JSON
{
  "name": "Maeve",
  "age": 28
}

// ✓ Valid JSON - No errors

Related JSON validation & formatting tools

Combine these tools with validation to improve data quality and streamline JSON workflows.

Format JSON

Format and prettify validated JSON for readability and consistent indentation.

Repair JSON

Automatically fix common JSON syntax issues found during validation.

Compare JSON

Compare validated JSON files to spot differences and track changes.

Schema Generator

Generate JSON Schema from validated JSON for validation and documentation.

Frequently Asked Questions

What does JSON validation check?

JSON validation checks whether your JSON is syntactically correct and structurally sound, and provides statistics such as type counts, nesting depth, and payload size.

What kinds of errors will I see?

Common errors include missing commas, unclosed braces/brackets, invalid escape sequences, trailing commas, and malformed strings.

What are the warnings about?

Warnings highlight potential risks such as very deep nesting, extremely long strings, or unusual patterns that may cause downstream issues even when the JSON is valid.

Can I download a validation report?

Yes. Use Report to download a JSON validation report that includes errors, warnings, and statistics.

JSON Validator - Syntax Checker & Error Detector | JSONSwiss