“Mobile First” is the given name to the model of platforms development that requires a first thought in the mobile devices. According to the worldwide boom of the mobile technology, today is necessary work in versatile designs taking always into account users from small screens, but what does it mean to design in small screens?The development of digital platforms leaded to smartphones and tablets users, has a different needs in te creation in navigable sites in desktop devices, especially in design. Below some of them: Content organization: One of the biggest design chllenge under the “Mobile Fisrt” philosophy, is to offer a content structure to a different user, (With differents navigable behaviors. For this consumer, content must be stacked from top to bottom according to the narrow Edge from the devices that day in day out are used in vertical direction. Noticeably this conditions the hierarchy of contents. Application forms: If you want to translate application forms in real conversión, they should be design according to the user needs from mobile devices. First of all, the should follow a vertical direction also it should have the less gaps posible and offer predictive answers that allows users optimize time and reduce typing errors. Menus: Menus with multiple categories and sub-categories work great for desktop users, but on mobile devices the fingers and screen size requires a single-level reading menu design, with enough large texts and buttons, as well as a vertical alignment for menus that contain several options While there are other variables to consider in terms of design and content, these are some of the most relevant. In any case, now the most important thing when designing platforms is to always keep in mind the different ways in which users browse and consume information from their smartphones, tablets, wearables, etc.