@Bastien_Siebman
One of my customers used to track their time in Harvest, but it was too expensive for their needs. Now they have Asana, and as they just want to have a rough estimation of time spent on each of their project (to have a conversation with their customer if they spend too much time on it), they added a “Time” column in their projects, and either track time for their tasks (which are quite high-level) or they have a section with one task for each project member, where they add manually the time they spent, and if needed, they see the total amount of time for the project.
Otherwise, I know that @Solene_Verhaeghe suggested Clockify to one of her customers. One of the benefits is that you can record time directly in a task, there is a timer. But you have to manually create all the projects in Clockify, there is no sync between project list in Asana and project list in Clockify. And the reports are in Clockify.