JSON Formatters Across Operating Systems: A Feature Comparison

Working with JSON data is commonplace for developers. Whether you're debugging API responses, configuring applications, or processing data, dealing with unformatted, minified, or inconsistent JSON can be challenging. JSON formatters (also known as beautifiers or pretty-printers) are essential tools that transform messy JSON strings into a human-readable, indented structure.

While the core task is simple – adding whitespace and line breaks – the tools available and their specific features can vary significantly depending on the operating system you are using. This guide compares some popular methods and tools for formatting JSON on Windows, macOS, and Linux, highlighting their features and how to use them.

Common Formatting Features

Most JSON formatters offer a range of features beyond simple indentation. Here are some key capabilities to look for:

• Pretty-Printing / Indentation: The primary function. Adds spaces or tabs to make the structure clear. Tools often allow customizing the indentation width (e.g., 2 spaces, 4 spaces, tabs).
• Minifying / Compacting: The opposite of pretty-printing. Removes all unnecessary whitespace to produce the smallest possible JSON string, useful for reducing file size or network payload.
• Key Sorting: Sorts the keys within JSON objects alphabetically. This makes comparing different JSON objects easier and ensures consistent formatting.
• Validation: Checks if the input string is valid JSON before attempting to format it. Invalid JSON cannot be reliably formatted and will often cause errors.
• Colorization: Some tools, especially command-line ones, can output formatted JSON with syntax highlighting for better readability in the terminal.

Cross-Platform Command Line Tools

For developers comfortable with the command line, these tools offer powerful and scriptable ways to format JSON across different operating systems.

jq (Linux, macOS, Windows)

jq is often called the "sed, awk, grep for JSON". While it's a powerful JSON processor for filtering, transforming, and selecting data, its simplest use case is formatting. It needs to be installed separately but is available via package managers (like apt, brew, choco) on all major platforms.

echo '{"name":"Alice","age":30,"city":"New York"}' | jq '.'

{
  "name": "Alice",
  "age": 30,
  "city": "New York"
}

echo '{
  "name": "Alice",
  "age": 30,
  "city": "New York"
}' | jq -c '.'

{"name":"Alice","age":30,"city":"New York"}

echo '{"city":"New York","name":"Alice","age":30}' | jq '. | sort_keys'

{
  "age": 30,
  "city": "New York",
  "name": "Alice"
}

jq is highly flexible, supporting various indentation levels (e.g., jq --indent 4) and complex transformations. It's an excellent choice if you frequently work with JSON from the command line or need scripting capabilities.

OS-Specific Tools

Many operating systems come with scripting languages or utilities that can be leveraged to format JSON without installing external tools like jq.

Windows (PowerShell)

PowerShell includes cmdlets for working with JSON. ConvertFrom-Json parses a JSON string into a PowerShell object, and ConvertTo-Json converts a PowerShell object back into a JSON string.ConvertTo-Json automatically pretty-prints by default and supports depth control.

@'
{"name":"Alice","age":30,"city":"New York"}
'@ | ConvertFrom-Json | ConvertTo-Json

{
    "name": "Alice",
    "age": 30,
    "city": "New York"
}

@'
{"person":{"name":"Alice","details":{"age":30,"city":"New York"}}}
'@ | ConvertFrom-Json | ConvertTo-Json -Depth 2

{
    "person":  {...}
}

@'
{"person":{"name":"Alice","details":{"age":30,"city":"New York"}}}
'@ | ConvertFrom-Json | ConvertTo-Json -Depth 5

{
    "person":  {
                   "name": "Alice",
                   "details":  {
                                   "age": 30,
                                   "city": "New York"
                               }
               }
}

PowerShell's JSON cmdlets are built-in and convenient for simple formatting, especially within PowerShell scripts. However, they lack the advanced features of jq like key sorting or complex data manipulation.

macOS & Linux (Python, Perl)

Both macOS and most Linux distributions come with Python and Perl pre-installed, both of which have modules for working with JSON that can be easily accessed from the command line.

Using Python's json.tool

Python's standard library includes a simple JSON encoder/decoder with a command-line interface for validation and pretty-printing.

echo '{"name":"Alice","age":30,"city":"New York"}' | python -m json.tool

{
    "name": "Alice",
    "age": 30,
    "city": "New York"
}

echo '{"name":"Alice","age":30,"city":"New York"}' | python -m json.tool --indent 2

{
  "name": "Alice",
  "age": 30,
  "city": "New York"
}

echo '{"city":"New York","name":"Alice","age":30}' | python -m json.tool --sort-keys

{
    "age": 30,
    "city": "New York",
    "name": "Alice"
}

Python's json.tool is a great built-in option that handles basic pretty-printing, indentation customization, and key sorting. It's often sufficient for quick command-line formatting tasks.

Using Perl's json_pp or jshon

Perl's JSON::PP module provides the json_pp command-line utility (or sometimes available via the cpanminus installed jshon, depending on the system/installation). It's another simple, built-in option on systems with Perl.

echo '{"name":"Alice","age":30,"city":"New York"}' | json_pp

{
   "age" : 30,
   "city" : "New York",
   "name" : "Alice"
}

echo '{
   "age" : 30,
   "city" : "New York",
   "name" : "Alice"
}' | json_pp -json_opt UTF8,canonical

{"age":30,"city":"New York","name":"Alice"}

json_pp is simple and available but might have fewer options for indentation styles compared to Python's tool or jq. The canonical option also sorts keys.

GUI Tools & Editors

Many graphical text editors (like VS Code, Sublime Text, Atom, Notepad++) and dedicated GUI JSON viewers/editors include built-in or plugin-based JSON formatting capabilities. These are often very user-friendly, offering a one-click format option. Online JSON formatters are also widely available. While not OS-specific command-line tools, they are a common way developers format JSON interactively.

Feature Comparison Summary

Here's a quick comparison of the command-line tools discussed:

Choosing the Right Tool

The best JSON formatter depends on your needs and environment:

• For quick, interactive formatting within a text editor, use its built-in features or plugins.
• If you need a powerful, flexible tool for scripting, filtering, and transforming JSON on any platform, install and learn jq. It's the de facto standard for command-line JSON processing.
• If you are on Windows and primarily work within PowerShell, ConvertTo-Json is a convenient built-in option for basic pretty-printing.
• On macOS or Linux, the built-in Python or Perl tools (python -m json.tool, json_pp) are excellent for basic formatting and validation without any installation. python -m json.tool offers good control over indentation and key sorting.
• For validating JSON files, piping the content through any of these tools will typically throw an error if the JSON is invalid, making them simple validators.

Conclusion

While the goal of JSON formatting is consistent, the tools and their capabilities vary across operating systems. Understanding the strengths of built-in utilities like PowerShell's ConvertTo-Json, Python's json.tool, and Perl's json_pp, as well as the power of dedicated cross-platform tools like jq, allows developers to choose the most efficient method for their specific task and environment. For serious command-line JSON manipulation, investing time in learning jq is highly recommended due to its versatility. For simple, everyday formatting, the built-in options are often more than sufficient.