Picto thématique

Rule n° 219 - The server transmits compressed contents to the clients which accept them.

This is a particularly effective way of speeding up page access time and reducing bandwidth costs: a server can be configured to send compressed pages (in a format similar to that of a .zip archive). The contents are then "unzipped" on the fly and in a totally transparent manner on the user's workstation.

#Eco-conception #Server and performance #Development


  • Improve the speed of the page’s rendering.
  • Reduce bandwidth costs.
  • Reduce the energy impact related to the consultation of the site.


Activate the server's Gzip or Deflate module to compress JavaScript, CSS and HTML resources.


For each page checked:

  • Check the content compression (Gzip) using a dedicated tool.

Be careful to check all of the linked elements (CSS, JS, HTML) and not just the page itself. Formats such as JPEG or PNG images or zip files which are already compressed, for example, should not be recompressed. If

the size before compression of an element is less than 1 kB, it is not necessary to compress it, because the size might increase.

By Opquast - Read the license

Overview and background

The 240 Opquast rules are defined and agreed upon by an extensive community of web professionals and academics. These web quality assurance guidance rules started as a list of best practices 20 years ago. They have since been revised every five years and have been tried and tested via millions of web interactions by Opquast community’s customers, including the leading CMS communities which have developed plugins for WordPress, Drupal and Prestashop. The most recent version, v4, was established in 2020.

Each rule has individual technical sheets and the rules can be searched by project phase or various topics: e-commerce, data-privacy, internationalization, security, code, etc, or by themes: accessibility, SEO, mobile, privacy, and ecodesign. The complete checklist is available on a creative commons license BY-SA.

To learn more about the Opquast approach, read this article published at Smashing Magazine

Broad application and benefits

The rules should be applied to your projects from the design phase through to post-implementation , and they should be understood by all professionals with web and customer experience (CX) responsibilities: from strategy to operations, marketers to project managers, and editorial to technical staff. The benefits of using this ruleset are numerous, including improving customer satisfaction, web performance, and e-commerce, and expanding your client base, while also decreasing your errors and costs.

Multidisciplinary verticles - accessiiblity, SEO, e-commerce, ecodesign etc..- starting from the foundational Opquast base.

Discover Opquast training and certification

The objective of these rules and the Opquast community mission is ‘making the web better’ for your customers and for everyone! Opquast rules cover the key major areas of risk that can negatively affect website users such as privacy, ecodesign, accessibility and security.

Opquast training has already allowed over 17,000 web professionals to have their skills certified. Train your teams, contact us

We offer a 1 hour free discovery module.