Testing the Effects of Cann'App, a Digital Intervention for Cannabis Harm Reduction

The goal of this clinical trial is to learn if a digital web application can prevent the risks related to cannabis use among adult regular cannabis users who are enrolled in a pilot trial for cannabis sales regulation conducted in Lausanne, Switzerland (i.e., Cann-L study) and have agreed that their data were used in other studies. The main question it aims to answer is: Do participants who have access to the intervention modules of the web application raise their use of protective behavioral strategies to lower cannabis-related risks? Researchers will compare the intervention modules to a control module (i.e., information on cannabis-related risks and harm reduction) to see if the web application works to prevent the risks related to cannabis use. They will also compare intervention modules across each other to see whether one works better than another. Participants will: * Create a user account in the web application * Access the web application using a laptop, tablet or smartphone * Use the web application as they wish throughout the duration of the study * Complete the regular Cann-L study questionnaires every six months, which will be used to measure their cannabis use and related risks.