JSON Formatting Guide: Validate, Format & Debug Like a Pro

What is JSON?

JSON (JavaScript Object Notation) is the most popular data format for APIs and web applications. It's human-readable, language-independent, and supported by virtually every programming language.

JSON Syntax Rules

1. Data is in key-value pairs

2. Keys must be strings (in double quotes)

3. Values can be: string, number, boolean, null, array, or object

4. Data is separated by commas

5. Objects use curly braces {}

6. Arrays use square brackets []

Common JSON Errors

Missing or extra commas

// Wrong - trailing comma
{ "name": "John", "age": 30, }

// Correct
{ "name": "John", "age": 30 }

Single quotes instead of double

// Wrong
{ 'name': 'John' }

// Correct
{ "name": "John" }

Unquoted keys

// Wrong
{ name: "John" }

// Correct
{ "name": "John" }

Comments in JSON

// Wrong - JSON does not support comments
{ "name": "John" /* this is a user */ }

// Use JSONC or JSON5 if you need comments

Use our JSON Formatter to instantly validate and pretty-print your JSON.

JSON Best Practices

1. Consistent naming conventions

Pick camelCase or snake_case and stick with it:

{ "firstName": "John", "lastName": "Doe" }
// or
{ "first_name": "John", "last_name": "Doe" }

2. Use meaningful key names

// Bad
{ "n": "John", "a": 30 }

// Good
{ "name": "John", "age": 30 }

3. Use arrays for lists, not numbered keys

// Bad
{ "item1": "Apple", "item2": "Banana" }

// Good
{ "items": ["Apple", "Banana"] }

4. Use null for missing values

{ "name": "John", "middleName": null, "age": 30 }

Working with JSON Data

Converting CSV to JSON

Many datasets come as CSV files. Use our CSV to JSON Converter to transform spreadsheet data into structured JSON.

JSON and YAML

YAML is a JSON superset often used for configuration files. Convert between them with our YAML Formatter.

JWT Tokens

JWTs are Base64-encoded JSON. Decode and inspect them with our JWT Decoder.

Base64 Encoding

Sometimes JSON needs to be embedded in URLs or headers as Base64. Use our Base64 Encoder for quick encoding/decoding.

JSON Performance Tips

1. Minimize payload size - remove unnecessary fields

2. Use compression - gzip/brotli for API responses

3. Paginate large responses - don't send thousands of records at once

4. Use JSON streaming - for very large datasets, stream line by line

5. Cache responses - ETags and Cache-Control headers

Debugging JSON APIs

When an API returns unexpected JSON:

1. Validate the JSON - paste it into our formatter to check for syntax errors

2. Check content type - ensure the response header is "application/json"

3. Inspect nested objects - use the tree view to navigate complex structures

4. Compare responses - use our Text Diff tool to compare two API responses