JSON Validator
Instantly check if your JSON is valid. Get exact error location and line numbers — all in your browser.
How to Use the JSON Validator
- Paste Your JSON — Copy your JSON from an API response, config file, or any source and paste it into the input area.
- Click Validate JSON — The tool parses your input and checks the syntax immediately.
- Read the Results — A green badge confirms valid JSON; a red badge shows the exact error message and position.
- Fix and Re-validate — Correct any errors shown in the input area and click Validate again.
- Inspect the Tree — For valid JSON, expand the syntax-highlighted tree to verify structure and data types.
Key Features
Exact Error Location
Shows the precise line number and character position of any syntax error, not just a generic failure message.
Instant Validation
Validates JSON using the browser's native parser — the same engine that processes JSON in real applications.
Tree Preview
Displays valid JSON as a syntax-highlighted tree for easy inspection of keys, values, and nesting levels.
Duplicate Key Warning
Detects duplicate keys that could cause silent data loss in certain JSON parsers.
100% Client-Side
All validation runs in your browser — your JSON data is never sent anywhere.
JSON Stats
See total character count, key count, and nesting depth after successful validation.
How JSON Validation Works
JSON validation uses the browser's built-in JSON.parse() function to check whether a string is syntactically correct JSON. This is the same parser used by every JavaScript application, so the result is authoritative.
When the parser throws a SyntaxError, the error message contains the character position where the parser encountered unexpected input. The validator extracts this position and presents it clearly alongside your input so you can find and fix the issue.
Practical Examples
🇮🇳 Ankit Verma, Delhi — API Config Validation
Ankit pasted his Razorpay webhook config JSON. The validator caught a trailing comma after the last key — a common copy-paste error from JavaScript code.
Error: Unexpected token } at position 87
🇮🇳 Divya Menon, Kochi — Firebase Rules Check
Divya validated her Firebase Realtime Database rules JSON before deploying. The validator confirmed the structure was valid and showed 12 keys across 3 nesting levels.
✔ Valid JSON — 12 keys🇬🇧 James Wright, London — REST API Response
James tested an API response that was failing silently in his Node app. The validator found that a string value contained an unescaped newline character, which made the JSON technically invalid.
✖ Unescaped newline fixedWhat Is JSON Validation?
JSON validation is the process of checking whether a string strictly conforms to the JSON specification (RFC 8259). Valid JSON must use double quotes around all keys and string values, cannot have trailing commas, cannot include JavaScript comments, and must use only the data types defined in the spec: strings, numbers, booleans, null, objects, and arrays.
Validation is distinct from formatting: a JSON string can be valid but unreadable (minified), or it can be formatted but syntactically invalid (containing a typo). This tool checks validity; our JSON Formatter handles presentation.
Want a deep dive into JSON validation and common errors? Read our blog post.
📖 Read: JSON Validation — Common Errors and How to Fix Them →Frequently Asked Questions
Is this tool free to use?
Yes, the JSON Validator on StoreDropship is completely free with no registration required.
What is JSON validation?
JSON validation checks whether a JSON string conforms to the JSON specification — proper syntax, correct quote style, no trailing commas, and valid data types.
Does the validator show where the error is?
Yes, the validator displays the error message from the parser including the line and character position of the syntax error.
What's the difference between JSON validation and JSON schema validation?
JSON validation checks syntax (is it valid JSON?). JSON schema validation checks structure (does it match a defined schema?). This tool checks syntax.
Is my data safe?
Yes. All validation runs in your browser. No data is ever transmitted to a server.
Why does my JSON fail validation?
Common reasons: trailing commas, single quotes instead of double quotes, unquoted keys, comments in the JSON, or JavaScript-specific values like undefined.
Can I validate JSON arrays?
Yes, the validator handles JSON objects, arrays, nested structures, and primitive values.
Does the tool check for duplicate keys?
The tool warns about duplicate keys which, while technically not invalid per the spec, can cause unpredictable behaviour in parsers.
Can I use this for API testing?
Yes, paste API responses directly into the validator to confirm they are well-formed before processing them in your code.
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