Visual Design Comparison of Popular JSON Formatters

JSON (JavaScript Object Notation) is the de facto standard for data interchange on the web. While the format itself is strictly defined, how it's presented to a human reader can vary significantly depending on the tool used. JSON formatters (also known as beautifiers or pretty-printers) are essential utilities for making raw, compact, or minified JSON readable. Beyond just adding whitespace, their visual design plays a crucial role in usability, particularly for debugging, code reviews, and understanding complex data structures.

This page explores the visual design aspects that differentiate popular JSON formatters and how these choices impact the developer's experience.

Key Visual Design Elements

When we talk about the visual design of a JSON formatter, we're looking at several factors that affect readability:

• Indentation Style & Spacing: The number of spaces or tabs used for indentation. Common choices are 2 spaces, 4 spaces, or tabs. This affects the horizontal spread of the data.

  2 spaces

  {
    "name": "Alice",
    "age": 30
  }

  4 spaces

  {
      "name": "Bob",
      "city": "New York"
  }

  Tabs (often displayed as 4 spaces)

  {
  	"user": "Charlie",
  	"active": true
  }

• Whitespace Usage: Beyond indentation, formatters may add spaces around colons (`:`) or commas (`,`) to improve spacing.

  With spaces around colon and after comma

  {
    "key" : "value",
    "another" : 123
  }

  More compact (less common in formatters)

  {
    "key":"value",
    "another":123
  }

• Syntax Highlighting: Using different colors to distinguish between keys, strings, numbers, booleans, null, and structural characters (braces, brackets, commas, colons). Keys, Strings, Numbers, Booleans/Null, Structure. This is arguably the most impactful visual element for quick scanning.
• Expand/Collapse Functionality: For deeply nested JSON, the ability to collapse objects () and arrays () is invaluable for focusing on relevant sections and managing complexity. This is a feature found in many online formatters and IDEs.
• Error Highlighting: Clearly indicating syntax errors with visual cues like red underlines () or error messages next to the offending line.
• Data Type Glyphs: Some advanced tools might show small icons indicating the data type of each value (e.g., ``, `[]`, `"A"`, `123`).
• Line Numbers: Simple but crucial for locating data points or errors referenced by line number.
• Diffing Views: Tools that compare two JSON structures often use highlighting () to show added, deleted, or modified lines/values.

Common Formatting Styles & Their Impact

Different formatters adopt varying default styles. Let's look at how some common approaches affect readability:

Compact vs. Expanded

Minified JSON has no extra whitespace. Expanded JSON adds newlines and indentation. The degree of expansion can vary. Some formatters might keep short arrays or objects on a single line, while others strictly put each element on a new line.

{"id":1,"name":"Test","tags":["A","B","C"],"details":{"version":2,"active":true}}

{
  "id": 1,
  "name": "Test",
  "tags": ["A", "B", "C"],
  "details": { "version": 2, "active": true }
}

{
  "id": 1,
  "name": "Test",
  "tags": [
    "A",
    "B",
    "C"
  ],
  "details": {
    "version": 2,
    "active": true
  }
}

Indentation Size (2 vs 4 spaces)

This is largely a matter of preference and coding style consistency.

{
  "config": {
    "setting1": "value",
    "nested": {
      "itemA": 1
    }
  }
}

{
    "config": {
        "setting1": "value",
        "nested": {
            "itemA": 1
        }
    }
}

Syntax Highlighting Schemes

The choice of colors is highly subjective but plays a massive role in scanning efficiency. Good syntax highlighting makes it easy to quickly identify different data types and structural elements. Dark mode vs. light mode support is also a key aspect for many developers. Consistency in color schemes across different tools (IDEs, online formatters) reduces cognitive load.

Comparing Approaches & Usability

Different tools cater to different needs, and their visual design reflects this:

• Simple Online Formatters: Often focus on basic indentation (usually configurable between 2, 4 spaces, or tabs) and standard syntax highlighting. They might offer minification as an option. Examples: jsonformatter.org, jsonlint.com. Their design is typically clean and functional.
• IDE Built-in Formatters: Integrate deeply with the code editor's theme and settings. They use the same syntax highlighting engine and often allow customization of indentation size. They benefit from IDE features like folding/collapsing nodes directly in the editor tree view.
• Browser Developer Tools: The "Network" tab in browser dev tools often includes a "Preview" or "Response" panel that formats JSON. These are highly optimized for viewing API responses, featuring expandable/collapsible nodes and sometimes basic filtering or search. Their design is usually part of the browser's overall dev tool UI.
• Dedicated Desktop/Web JSON Viewers: Tools like Postman, Insomnia, or specialized JSON viewers (like JSON Viewer Pro extension for Chrome) offer richer visual experiences. They might have tree views alongside the raw text, advanced search, filtering, and diffing capabilities. Their visual design often prioritizes navigation and data exploration alongside simple formatting.

Which Design is "Best"?

There's no single "best" visual design, as it depends on the context and personal preference:

• For quick readability during coding or debugging in an IDE: Consistent indentation and good syntax highlighting are key. Expand/collapse is a must for large files.
• For reviewing API responses: Expandable/collapsible tree views like those in browser dev tools or API clients are superior for exploring nested data.
• For comparing two JSON files: A clear diffing visualization is paramount.
• For simple, one-off formatting: A straightforward online tool with configurable indentation works perfectly.

Conclusion

While the underlying JSON structure is standard, the visual presentation by formatters profoundly impacts how easily developers can read, understand, and debug JSON data. Factors like indentation style, whitespace, syntax highlighting, and interactive features like expand/collapse and diffing are crucial design considerations. Understanding these differences helps developers choose the right tool for the task and appreciate how good visual design enhances usability and efficiency when working with JSON.

Ultimately, the "best" formatter for you will likely be one whose visual style aligns with your personal preferences and the specific task you're performing, whether it's a quick format, deep inspection, or complex comparison.