Python/Django/PostgreSQL/SQLite/Firebase: ? RESTful API backend server for administrative collection services, using Dart/Flutter for the frontend on Android/iOS. ? Backend API server for standardization of processes and procedures on hotel housekeeping, with evaluation system (survey type). Besides, its frontend developed with HTML5/CSS3/Javascript/Knockout/DevExtreme on the web, and Dart/Flutter/Java on the Android side, and Flutter/Swift on the iPad/iPhone side. ? API server for inventory control of nutrient products in plantings of different areas (nano-nutrients). Also, frontend developed using web tech and Flutter/Java/Swift on the Android/iOS side.