JSON Validator
Check JSON syntax locally and read an error without changing the input. Free, with no signup or usage-count limits.
Free · No signup · No watermark · On-device processing
Use the tool
How to use JSON Validator
- Paste a complete JSON value into the input.
- Run validation and read the syntax result or browser error.
- Correct errors in the original input and validate again.
Understand the input and output
Validation accepts a complete JSON value: an object, array, string, number, boolean or null. The original input is retained, so validation never rounds or rewrites number tokens.
Comments, trailing commas and single-quoted strings are not JSON. This checks syntax, not a JSON Schema. Duplicate names are accepted by the native parser and are not diagnosed.
Privacy and browser support
Your input is handled in this browser tab. Selected files and entered text are not sent to Varento Tools by this tool. Some specialized libraries load only when needed. A browser with JavaScript and sufficient device memory is required. Read our local-processing explanation.
Related tools
Frequently asked questions
Is this tool free without daily usage limits?
Yes. Varento Tools has no signup, accounts, usage-count caps, paywalls or watermarks. Device memory, format support and browser restrictions can still limit technically demanding files.
Does validation change large integers?
No. The original text remains untouched. JavaScript may approximate a number internally while parsing, but this validator does not serialize that parsed value back into your input.
Is my input uploaded?
No. This tool processes your input in the current browser tab and does not send it to a processing server.
What are the practical limits?
Comments, trailing commas and single-quoted strings are not JSON. This checks syntax, not a JSON Schema. Duplicate names are accepted by the native parser and are not diagnosed.