Picto thématique

Rule n° 130 - The server respects the preferential order of languages specified by user agents.

Each request to a server may include information about language preferences. Each Internet user can classify his or her preferred languages in his or her browser. The server must offer the contents in the order requested by the user. If the user indicates French, then Spanish, then English, the server must serve the page in French if it exists, otherwise in Spanish if it exists, and otherwise in English if it exists.

#Accessibility #Internationalization #Development


  • Priority is given to sending the user the version of the page corresponding to the language he or she has indicated in the preferences the user agent tool.


Use server-specific content negotiation, testing the accept-language HTTP header values.


For a website available in several languages (French and English, for example):

  • Modify your browser options to choose your favourite language: select, for example, English as the preferred language;
  • Type the main URL of the website in this same browser and check that the contents of the page are available in the favourite language. In our example, the English version should be automatically returned.
  • Perform the same test by choosing another preferred language in the browser options.

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.