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Source code for Web Bloat Score Calculator:
JavaScript C# HTML Batchfile CSS
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LICENSE Grammar fixes Jan 20, 2020


Live demo of Web Bloat Score Calculator:

How to run the project

WebBS-Calculator uses the SlimmerJS scriptable browser that requires Firefox version 48 or older to be installed on your computer. You can download it from Mozzila's archive.

If you don’t choose the default install location (C:\Program Files\Mozilla Firefox 48\firefox.exe), you need to let SlimmerJS know by modifying the WebBloatScore/Slimerjs/slimmer.bat file on lines 202 and 203 with the path you chose during the installation.

After that you can simply run the WebBloatScore ASP.NET MVC application.


As described on, the web bloat score is calculated as WebBS = TotalPageSize / PageImageSize

In the project the calculation is happening in the SlimmerExecutor class:

  1. First SlimmerJS is executed. It creates and stores a screenshot of the web page and returns the total size of the page.
  2. After that PngQuant library is used to optimize the screenshot of the page.
  3. In the end the result with all values necessary to calculate WebBS is returned.


The tasks necessary to calculate the score are time-consuming and depending on the hardware can take several minutes to complete. Therefore the timeout is used to limit the execution time. On top of that caching of the most used websites is used to save resources.

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