Instant Validation
Get real-time feedback as you type. Our validator checks your JSON syntax instantly without any delays.
Online JSON Validator
Validate your JSON syntax instantly in the browser. Detailed errors with exact line numbers. Core validation is included on the free tier; optional Pro upgrades AI limits elsewhere.
Why Use Our JSON Validator?
Detailed Error Messages
Pinpoint exact error locations with line numbers, column positions, and clear descriptions of what went wrong.
Validates locally
Validation runs in your browser, so your JSON does not leave your device for this step. Optional site features (snapshots, AI repair) handle data differently if you use them—see the privacy policy.
AI-Powered Auto-Fix
Found an error? Let our AI automatically fix common JSON syntax issues with a single click.
File Upload Support
Upload JSON files directly from your computer. Supports large files for comprehensive validation.
Free tier, local checks
Validation runs in your browser on the free tier—no subscription required for unlimited syntax checks. Optional Pro upgrades AI and file limits elsewhere.
How to Validate JSON Online
1
Paste or Upload Your JSON
Copy your JSON data and paste it into the editor, or click the upload button to select a JSON file from your computer.
2
View Instant Results
BracketView automatically validates your JSON as you paste. Valid JSON shows a success indicator, while errors display detailed messages.
3
Fix Errors or Auto-Repair
Use the detailed error messages to manually fix issues, or click the "Fix with AI" button to automatically repair common syntax errors.
Common JSON Errors We Detect
Missing Commas
{"name": "John" "age": 30}Missing comma between properties
Trailing Commas
{"name": "John", "age": 30,}Extra comma after last property
Unquoted Keys
{name: "John", age: 30}Property names must be in double quotes
Single Quotes
{'name': 'John'}JSON requires double quotes, not single quotes
Unclosed Brackets
{"items": [1, 2, 3}Missing closing bracket for array
Invalid Values
{"active": True}Boolean values must be lowercase (true/false)
Frequently Asked Questions
What is JSON validation?▼
JSON validation is the process of checking whether a JSON string follows proper syntax rules. Valid JSON must have properly quoted keys and strings, correct use of brackets and braces, proper comma placement, and valid data types (strings, numbers, booleans, null, arrays, and objects).
What common JSON errors does the validator detect?▼
BracketView detects: missing or extra commas, unquoted property names, single quotes instead of double quotes, trailing commas after last items, unclosed brackets or braces, invalid escape sequences, duplicate keys, and malformed values.
Is the JSON validator free to use?▼
Yes. The validator runs locally in your browser on the free tier with unlimited syntax validation—no paywall. Pro is optional for AI and higher caps on other tools. See pricing.
Is my JSON data secure?▼
For validation, everything runs locally in your browser and your JSON does not leave your device during that step. Other optional tools (snapshot links, AI repair) may upload or send data when you use them—see the privacy policy.
Can I validate large JSON files?▼
Yes, BracketView can handle large JSON files efficiently. You can paste JSON directly or upload files from your computer for validation.