JSON Validator Online
Validate, format, minify, and fix JSON syntax errors instantly in your browser.
Use this free JSON Validator to check JSON syntax online, find formatting mistakes, and fix common JSON errors. Paste JSON, upload a .json file, or try the sample data. The tool validates your JSON in the browser and shows clear line and column hints when something is wrong.
Formatting options
Your Privacy Matters
All processing happens in your browser. Your JSON is never sent to our servers.
How to use JSON Validator
Follow these simple steps to use the tool.
- 1 Paste your JSON into the input editor.
- 2 The validator checks the syntax automatically.
- 3 If the JSON is invalid, check the error line, column, and hint.
- 4 Fix the input manually or use Try to Fix JSON.
- 5 When valid, format, minify, copy, or download the JSON.
Frequently Asked Questions
Answers to common questions about our JSON Validator tool.
What is a JSON validator?
A JSON validator checks whether JSON text follows valid JSON syntax. It helps find missing commas, missing quotes, trailing commas, invalid strings, unclosed brackets, and other syntax errors.
How do I validate JSON online?
Paste your JSON into the input box. The tool checks the syntax and shows whether the JSON is valid. If there is an error, it shows the line, column, and a short hint.
Does this JSON validator upload my data?
No. The MVP runs fully in the browser. JSON is not sent to a server, stored in logs, or shared with third-party APIs.
Why is my JSON invalid?
The most common reasons are trailing commas, missing commas, single quotes, unquoted object keys, comments, unclosed strings, invalid escape sequences, or values like undefined, NaN, and Infinity.
Are comments allowed in JSON?
No. Strict JSON does not support comments. If your file uses comments, it may be JSONC or a JavaScript object, not strict JSON.
Can JSON use single quotes?
No. JSON strings and object keys must use double quotes.
About JSON Validator
Validate JSON instantly in your browser. Paste JSON, upload a file, find syntax errors with line and column hints, format, minify, repair, copy, and download the fixed output.
Validate JSON Online
A JSON validator checks whether JSON text follows valid JSON syntax. It can identify missing commas, missing quotes, invalid trailing commas, unclosed brackets, invalid strings, and other syntax problems before the JSON is used in an API, app, or configuration file.
How to Use the JSON Validator
Paste your JSON into the input box. The tool checks the syntax in your browser, shows whether it is valid, and highlights the line and column where an error appears. If the JSON is valid, you can format, minify, copy, or download it.
What This JSON Checker Shows
This tool will display real-time validity status, line and column numbers of any errors, and character offsets. When errors are found, you will see a snippet pointing exactly to the problem with a human-readable hint.
Common JSON Errors This Tool Finds
Common JSON mistakes include missing commas, trailing commas, unquoted keys, single quotes, comments, invalid escape sequences, unclosed strings, unclosed arrays or objects, and invalid values such as NaN, Infinity, undefined, True, False, or None.
Format, Minify, and Copy Fixed JSON
Once your JSON is completely valid, you can format it with two or four spaces to make it readable. Alternatively, you can minify it for production use, then copy or download the results immediately.
Is This JSON Validator Private?
This JSON checker runs in your browser. Your input is not uploaded to a server for validation. For sensitive API keys, tokens, or production data, always review your organization’s security policy before pasting data into any online tool.