JSON formatter and validator
Read messy JSON and locate syntax errors.
Your inputs
Your results
Ready when you areYour results will appear here.
How it works
Parse strict JSON and export normalized pretty or compact JSON. Syntax failures appear beside the JSON field using the engine’s available error location.
Read the source reference ↗A few things to know
JSON does not allow comments, trailing commas, NaN or Infinity. Unsafe integers are rejected; duplicate keys keep the last value. Limited to 100,000 values and 100 nesting levels. Formatting does not validate a domain schema.
When to use this tool
Make strict JSON readable and locate syntax failures. Formatting normalizes whitespace while leaving the parsed value’s structure intact.
- Read an API payload.
- Format a configuration snippet.
- Find a JSON syntax mistake.
How to use json formatter and validator
Prepare the inputs
Paste the original text and keep a copy of it.
Choose the settings
Choose the conversion settings; identifiers are preserved as text.
Review and export
Review the output and download it before using it elsewhere.
Try the supplied example
Inputs
json: {"name":"Notebook","sku":"00123","active":true}; style: Pretty (2 spaces)
Result
The example formats a product object while preserving its quoted SKU.
What it means
Formatting is a syntax check, not confirmation that an API accepts those fields.
Common mistakes to avoid
Quote long numeric identifiers
Quote long numeric identifiers.
Syntax validity does not prove field correctness
Syntax validity does not prove field correctness.
Frequently asked questions
Definitions, edge cases, and practical next steps for this tool. Search all tool FAQs ↗
Are comments accepted?
No. Standard JSON excludes comments.
Can I keep trailing commas?
No. Remove them before formatting.
Does formatting preserve huge integers?
Only if they are quoted strings. JavaScript numbers can round integers beyond the safe range.
What about duplicate keys?
JSON.parse retains the last key value; inspect source carefully if duplicates matter.
Is an array valid JSON?
Yes. Arrays, strings, numbers, booleans and null can also be top-level JSON values.
Does this validate an API schema?
No. It checks syntax and formatting only.
Are my inputs uploaded or stored?
Processing happens locally in your browser. This tool does not upload inputs. Downloads stay on your device; sharing or opening them in another service is your choice.
What should I check before using the output?
JSON does not allow comments, trailing commas, NaN or Infinity. Unsafe integers are rejected; duplicate keys keep the last value. Limited to 100,000 values and 100 nesting levels. Formatting does not validate a domain schema.
Explore the topic in the blog
Sources and method
Use the references below to check definitions and platform guidance. The model’s scope and limits are explained above. Read our editorial standards.