Question 1

What is JSON and why is it so popular?

Accepted Answer

JSON (JavaScript Object Notation) was created by Douglas Crockford in the early 2000s. It became the de facto standard for web APIs because it's lighter than XML and natively understood by JavaScript. Fun fact: despite the name, JSON is language-independent and used in Python, Go, Rust, and virtually every modern language. Over 70% of public APIs use JSON as their primary format.

Question 2

What are the most common JSON syntax errors?

Accepted Answer

The top mistakes are:

Trailing commas after the last item (valid in JS, invalid in JSON)
Using single quotes instead of double quotes
Unquoted property names like {name: "value"} instead of {"name": "value"}
Including comments (JSON doesn't support them)
Using undefined or functions as values

Question 3

JSON vs YAML vs XML — what's the difference?

Accepted Answer

JSON: Strict syntax, widely supported, fast parsing, no comments. YAML: Supports comments, more readable, but whitespace-sensitive (popular for Docker, K8s configs). XML: Verbose but supports schemas, namespaces, and attributes. Each has trade-offs depending on your use case.

Question 4

Why does minified JSON load faster?

Accepted Answer

Minification removes all unnecessary whitespace, reducing file size by 10-30% typically. For a 100KB JSON payload, that's 10-30KB saved per request. At scale, this means faster downloads, lower bandwidth costs, and quicker parsing. The difference is negligible for small payloads but significant for mobile users or high-traffic APIs.

Question 5

Is my data secure when using this tool?

Accepted Answer

Yes, 100%. All validation and formatting happens locally in your browser using JavaScript. Your data never leaves your device — no server requests, no analytics on your content, no storage. You can verify this in your browser's Network tab or use the tool completely offline after the initial page load.

Question 6

Can JSON contain comments?

Accepted Answer

No, standard JSON doesn't support comments. This was an intentional design decision by Douglas Crockford to keep the format simple and prevent misuse. However, some tools support JSONC (JSON with Comments) or JSON5 which allows comments, trailing commas, and unquoted keys. Our validator uses strict JSON parsing.

Question 7

What's the maximum size for a JSON file?

Accepted Answer

JSON itself has no size limit, but practical limits exist: JavaScript's JSON.parse() can handle hundreds of MBs, but browsers may struggle with files over 50-100MB. For very large datasets, consider streaming parsers or formats like NDJSON (newline-delimited JSON) where each line is a separate JSON object.

Question 8

Pro tips for working with JSON

Accepted Answer

Use JSON.stringify(obj, null, 2) for pretty-printing in code
Validate API responses with JSON Schema for type safety
Use .json() on fetch responses instead of manual parsing
For config files, consider JSONC or JSON5 to add comments
Always handle JSON.parse() errors with try/catch

JSON

Frequently Asked Questions

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Frequently Asked Questions