How to Decode JWT Tokens Online — Header, Payload and Signature
Learn how JWT tokens work, how to decode their header and payload, and why signature verification requires a key.
How to Format and Validate JSON Online — Common Errors and Fixes
Learn how to format and validate JSON online, fix common syntax errors, and choose between beautified and minified JSON.
JSON is the default data format for APIs, web apps, configuration files and many developer tools. It is simple, but small syntax mistakes can break an API request or make an app fail to load. A missing quote, trailing comma or unquoted key can turn a valid-looking file into invalid JSON.
Utilao has two useful tools for this workflow: the JSON Formatter for beautifying, validating and minifying JSON, and the JSON Validator for checking syntax quickly.
When should you format JSON?
Format JSON when the data is hard to read. API responses are often returned as one long minified line. Formatting adds indentation and line breaks so you can understand the structure, inspect nested objects, find arrays, and locate the field you need.
Formatting does not change the data. It only changes whitespace. That makes it safe for debugging, documentation and development.
When should you validate JSON?
Validate JSON when you are editing it manually, receiving errors from an API, pasting config into an app, or checking data before deployment. A validator tells you whether the syntax is valid and helps identify mistakes.
Common JSON errors include trailing commas, single quotes, unquoted object keys, comments, missing brackets, extra brackets and invalid values like undefined or NaN.
Beautify vs minify JSON
Beautified JSON is easier for humans to read. It is best during debugging, learning, editing or documentation.
Minified JSON removes extra whitespace. It is best for production payloads, smaller files and faster transfer. The structure and values stay the same; only formatting changes.
How to format and validate JSON online
- Open the JSON Formatter or JSON Validator.
- Paste your JSON.
- Format it to make the structure readable.
- Validate it to catch syntax errors.
- Minify it if you need a compact production version.
FAQ
Does formatting JSON change the data?
No. Formatting only adds whitespace and indentation. The keys, values, arrays and objects remain the same.
Why is my JSON invalid?
The most common reasons are trailing commas, single quotes, unquoted keys, comments, missing brackets and values that are valid in JavaScript but not valid in JSON.
Can I minify JSON for production?
Yes. Minifying JSON is useful for reducing payload size while keeping the same data.