Online JSON Validator - Syntax Check & Error Location
Real-time JSON syntax check / pinpoint line & column / structure & type statistics
What Is a JSON Validator?
A JSON validator (also called JSON Lint) checks whether a JSON text complies with the standard syntax rules, so you can quickly find and pinpoint common formatting mistakes such as missing brackets, mismatched quotes, redundant or missing commas, and trailing commas. When the input is valid, the tool also shows a quick overview of its structure and data statistics so you can understand the shape of your data at a glance. To pretty-print the output afterwards, use the JSON Formatter; to shrink the size, use the JSON Compressor.
Common Use Cases
Development & debugging: when an API response is long, validate its format first, then locate the problematic field. Config file checking: validate a .json config file after editing so your app does not crash on startup. Data cleaning: validate JSON in bulk when importing third-party data, and filter out invalid records automatically. Front-end development: verify JSON before submitting a form so parsing errors surface early. API integration: during integration testing, validate both request and response payloads to keep the JSON formats in sync. To actually send and test an API request, pair it with the HTTP Test Tool.
Frequently Asked Questions
What is the difference between validating and formatting JSON?
Validation only checks whether the JSON syntax is legal and points out where errors occur; it never modifies your content. Formatting adds indentation and line breaks to beautify the output once the syntax check passes. If validation fails, formatting cannot proceed.
What errors can the JSON validator detect?
Unclosed braces {} or brackets [], mismatched quotes, missing or extra commas, JSON keys without double quotes, trailing commas, JS comments embedded in the JSON (not allowed by the standard), and unescaped special characters inside strings. The result shows the exact line and column so you can fix the issue quickly.
Is my JSON data leaked after validation?
No. All validation runs entirely on your device. Your data is never uploaded to any server, so it stays safe.
How do I fix a JSON that does not validate?
Start from the line the validator flags and check the brackets, quotes, and commas on that line and the one or two lines around it. Common causes include a missing closing bracket after a copy-paste, unescaped double quotes inside a string, or duplicated snippets merged by accident. When in doubt, walk upward from the reported line and verify that every {} and [] pair is properly closed.