JSON Formatters in Popular IDEs: Comparative Review

In modern web development and data exchange, JSON (JavaScript Object Notation) is ubiquitous. Working with JSON data, especially complex or large structures, can quickly become cumbersome if the formatting is inconsistent, unreadable, or minified. This is where JSON formatters come in handy. Built into or available as extensions for Integrated Development Environments (IDEs) and code editors, these tools automatically indent, space, and structure JSON code, significantly improving readability and maintainability.

This review delves into the JSON formatting capabilities of some popular IDEs, comparing their built-in features, configuration options, ease of use, and the ecosystem of related extensions. Understanding the nuances of how different IDEs handle JSON formatting can help developers choose the right tool or configuration for their workflow.

Why is JSON Formatting Important?

• Readability: Properly indented and spaced JSON is easy for humans to read and understand the hierarchical structure.
• Maintainability: Consistent formatting makes it easier to compare different versions of JSON data and spot changes.
• Debugging: Errors in JSON syntax are often easier to spot in a well-formatted file.
• Collaboration: Ensures a standard code style across teams, reducing merge conflicts related to formatting.

VS Code

Visual Studio Code (VS Code) is one of the most popular code editors today, known for its lightweight nature and extensive extension ecosystem. It offers robust built-in JSON support.

Built-in Formatting

VS Code includes a powerful built-in JSON language server that provides features like syntax highlighting, validation, and automatic formatting.

• Trigger Formatting: The default shortcut for formatting a document is often Shift+Alt+F on Windows/Linux or Shift+Option+F on macOS. You can also right-click and select "Format Document" or "Format Selection".
• Configuration: Basic formatting options like indent size (spaces or tabs) can be configured in VS Code's settings (`settings.json`). Look for settings under `"[json]"`. Common ones include `editor.tabSize`, `editor.insertSpaces`.
• Default Formatter: VS Code uses its built-in JSON formatter by default. If you install an extension that also provides JSON formatting, you might need to set the default formatter explicitly using the "Format Document With..." command.

Notable Extensions

While the built-in formatter is good, extensions can add extra features like sorting keys, removing comments (which are not standard JSON), or providing advanced validation.

• Prettier: A very popular opinionated code formatter that supports many languages, including JSON. It offers consistent formatting across projects, often configured via a `.prettierrc` file.
• JSON Tools: Provides various utilities, including validation, schema support, and alternative formatting styles.
• Sort JSON objects: A simple extension specifically for sorting keys within JSON objects alphabetically.

VS Code Pros

• Excellent built-in support, sufficient for most basic needs.
• Fast formatting, even for moderately large files.
• Vast extension ecosystem allows customization and added features (sorting, advanced validation).
• Easy to trigger formatting via shortcut or command palette.

VS Code Cons

• Built-in options are basic (mainly indentation).
• Requires extensions for advanced features like key sorting or stripping comments.

IntelliJ IDEA (and other JetBrains IDEs like WebStorm)

JetBrains IDEs like IntelliJ IDEA, WebStorm, PyCharm, etc., are known for their powerful, all-in-one development experience. They provide deep language understanding and sophisticated code analysis and formatting tools out-of-the-box.

Built-in Formatting

JetBrains IDEs have arguably some of the most comprehensive built-in formatting options available.

• Trigger Formatting: The standard shortcut to reformat code is Ctrl+Alt+L on Windows/Linux or Cmd+Option+L on macOS. This applies to the entire file or selected block based on your settings.
• Configuration: JetBrains IDEs offer very granular control over JSON formatting via the "Code Style" settings (File > Settings > Editor > Code Style > JSON). You can configure indentation, spacing around colons and commas, object brace style, array bracket style, and even whether to sort keys.
• Key Sorting: A notable built-in feature is the option to automatically sort JSON keys alphabetically during formatting. This is a common requirement that VS Code needs an extension for.

Extensions

While the built-in formatter is extensive, plugins can still enhance the experience, often by adding support for less common JSON variants or integrating with external tools.

• JSON Schema Plugin: Provides rich support for validating JSON against schemas, which ties in closely with understanding and formatting complex JSON.
• Integration with linters/formatters like Prettier or ESLint (with JSON plugins) is also possible, allowing the IDE's actions to defer to these external tools if preferred.

IntelliJ IDEA Pros

• Highly configurable built-in formatter.
• Built-in support for key sorting.
• Deep integration with the IDE's other features (validation, schema support).
• Consistent formatting experience across the entire JetBrains suite.

IntelliJ IDEA Cons

• Can feel more heavyweight compared to VS Code.
• Configuration options, while powerful, can be overwhelming for beginners.

Comparative Overview

Both VS Code and JetBrains IDEs offer excellent JSON formatting capabilities. The choice often comes down to personal preference, existing tooling, and the level of customization required.

Handling Invalid JSON

A common challenge is formatting JSON that contains syntax errors. Most formatters will fail or produce unexpected results when encountering invalid JSON.

• VS Code: The built-in formatter requires valid JSON. The language server will highlight syntax errors, guiding you to fix them before formatting can succeed. Extensions like JSON Tools might offer options to tolerate minor issues or attempt "repair".
• IntelliJ IDEA: Similarly requires valid JSON for reliable formatting. The IDE provides excellent syntax highlighting and error reporting to help identify issues quickly.

Tip: Always validate your JSON before attempting to format it if you're facing issues. Online validators or IDE syntax highlighting are your first line of defense.

Formatting Large JSON Files

Working with multi-megabyte JSON files can stress any formatter. Performance can become an issue, and some editors might struggle or even freeze.

• VS Code: Generally performs well due to its architecture, but extremely large files can still cause slowdowns depending on the specific extension or built-in logic.
• IntelliJ IDEA: Can sometimes be slower with extremely large files compared to VS Code, depending on the complexity of the formatting rules applied. However, it often handles large files robustly without crashing.

For truly massive JSON files (hundreds of MB or more), dedicated command-line tools or streaming parsers might be more appropriate than in-IDE formatting.

Best Practices and Tips

• Agree on a Style: Whether you use 2 spaces, 4 spaces, or tabs, consistency is key. Agree on a style within your team and configure your IDE accordingly.
• Use `.editorconfig`: Define your basic formatting rules (indent style/size) in an `.editorconfig` file at the root of your project. Most modern editors and IDEs respect this file, ensuring consistency across different tools.
• Integrate with Linters/Formatters: Tools like Prettier or ESLint (with JSON plugins) can automate formatting on save or commit hooks, ensuring code style consistency without manual effort. Configure your IDE to use these tools.
• Validate First: If formatting fails, the JSON is likely invalid. Use the IDE's error highlighting or an external validator to fix syntax issues before re-attempting to format.

Conclusion

Both VS Code and JetBrains IDEs (like IntelliJ IDEA and WebStorm) provide excellent tools for JSON formatting, greatly improving the developer experience when working with this common data format. VS Code offers a solid built-in formatter expandable via a rich ecosystem of extensions, making it a flexible choice. JetBrains IDEs, on the other hand, provide a highly configurable and powerful built-in formatter with features like key sorting included out-of-the-box.

For most developers, the built-in capabilities of either IDE will be more than sufficient. Those requiring specific advanced features (like key sorting without an extension in VS Code) or preferring deep configuration will find JetBrains IDEs particularly strong. Ultimately, the best formatter is the one that integrates seamlessly into your workflow, helps you maintain readable code, and ensures consistency across your projects.