11 useful tools for testing and optimizing CSS files

By reducing the CSS file size, the server will take less time to load, making the site faster. Using a CSS inspector capable of cleaning common errors can also help.

Optimizing your CSS stylesheet is a good way to speed up the loading of web pages or applications. By reducing the CSS file size, the server will take less time to load, making the site faster. Using a CSS inspector capable of cleaning common errors can also help.

In addition to optimization, the development of modern CSS is improved by a cleaner syntax. If you really want to improve your web development skills, CSS frameworks will allow you to do more with streamlined code.

The following tools and programs will help you to code more neatly, solve errors and improve syntax.

How to check and optimize CSS files?

  1. CSS code testing tool
    1. 1. PostCSS.org
    2. 2. CodeBeautify.org
    3. 3. CSSLint.net
    4. 4. BeautifyTools.com
    5. 5. W3C CSS Validator
  2. The tool makes the CSS code more tidy
    1. 6. CodeBeautifier.com
    2. 7. CSS Redundancy Checker
  3. Tool to optimize CSS code
    1. 8. CSSNano.co
    2. 9. CSSO
    3. 10. CSS Minify
    4. 11. PurifyCSS

CSS code testing tool

1. PostCSS.org

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PostCSS is not a simple code checker, but it is one of the most powerful options. That's why PostCSS has been used by Google, GitHub, WordPress, etc. PostCSS is an open source system that you can deploy in many applications to unlock a wide range of features through plugins.

These plugins can perform a lot of useful functions. There is an extensive library, but a few examples of what they can do are:

  1. Check the code to avoid errors
  2. Making code neat to make it easier to read
  3. Modify CSS to be more compatible with modern browsers

PostCSS is worth a try. This tool has strong support from the development community, helping PostCSS fit the needs of modern web development.

2. CodeBeautify.org

Code Beautify's CSS validator provides a CSS checker, which can make code more tidy. The CSS validator analyzes the code and provides suggestions to make it more efficient. It will issue a warning if the CSS can be modified and check for CSS code errors.

You can paste the manual CSS into the editor or provide the URL for your live site, then Code Beautify will automatically load the CSS for you.

3. CSSLint.net

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Consider another CSS helper, CSS Lint. Named after a relatively common term to 'clean up' the code, CSS Lint is an open source tool that will provide some useful tips for enhancing CSS code.

CSS Lint has a handy drop-down menu that lets you choose which potential errors you want to test. In case you find yourself having a specific problem, you can target that error and test the code.

4. BeautifyTools.com

Beautify Tools has a range of conversion tools and tools for web developers. Beautify Tools can go much further than CSS, but it has an integrated CSS validator. The web-based validator and make simple validation to test or format it for easier reading.

5. W3C CSS Validator

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The World Wide Web Consortium (W3C) is well known for its resources for helping web developers learn and grow. W3C offers its own CSS test engine, which has been around for almost a decade. There are many great resources for learning CSS and HTML. The W3C validator accepts raw code, URLs and uploads the CSS file to check the CSS syntax.

The tool makes the CSS code more tidy

6. CodeBeautifier.com

Error checking is useful, but developers have to work with mountains of code to understand the importance of a 'clean' format. Trying to work with code that is not properly placed can be a nightmare.

Code Beautifer is a CSS formatting tool that takes raw CSS code and outputs a 'clean' CSS table with improved features. You can choose from various checked options to get the code the way you want it. Code Beautifer also provides a built-in optimizer, with the option to export as a file.

7. CSS Redundancy Checker

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Avoiding redundant code is a good development principle. The same is true of CSS. As the stylesheet grows bigger and bigger, it's harder to maintain each small selector.

The CSS Redundancy Checker takes raw CSS code and shows you if any selector appears many times, to encourage you to group them and save the code. This will help reduce the final file size.

Tool to optimize CSS code

When you have finished validating your CSS and removing unnecessary code, you can get the best performance from your code by optimizing it.

One of the best ways to speed up the performance of CSS and your site is to minimize it. Minimize is the process of taking code and synthesizing certain elements so that the web browser can read it much faster.

This browser-friendly code is not like neatly formatted code. Instead, it can reduce variable names, delete comments, remove unused code, etc. - anything the browser doesn't need to render.

Here are some tools that can collapse your CSS.

8. CSSNano.co

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CSS Nano is a modern shortened tool for CSS scripts written in Nodejs.

CSS Nano works through the command line in the package integrated into the Node Package Manager (NPM) for JavaScript. CSS Nano also has an online web application that can perform instant conversions if you don't want to use the command line.

This tool performs various optimizations and uses PostCSS. As mentioned before, PostCSS is rated very well. CSS Nano builds on that power and reliability.


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CSSO is a simple web tool that takes raw CSS and minimizes it with a few options.

One of them is options for refactoring and optimizing code, making the CSS format more readable. You can select both at once to combine the two settings.

10. CSS Minify

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CSS Minify has fewer options than other advanced tools, but it works very well. It accepts raw code and uploads files to import CSS.

11. PurifyCSS

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PurifyCSS is a library that provides another way to optimize CSS. Instead of changing the CSS file, you run PurifyCSS on your entire application. It will parse the application and remove all CSS that is not in use by the application.

This can be especially helpful if you use the CSS framework. The framework provides many options but is quite heavy because of the amount of CSS needed to build the framework. PurifyCSS can take applications after you use the framework and go into the code center, removing unused CSS.

Hopefully, the tools listed here are sufficient for you to adjust and optimize your CSS stylesheet. Web developers are always eager for the opportunity to access new tools to upgrade their web development skills.

If you've used any of the tools that are more useful than those mentioned above, share them with everyone in the comments below!