** Introduction ** This app is a spirit level app. You can easily check the horizontal level and vertical level with your smartphone that you always carry with you. You can check the level with the bubbles that you are accustomed to, and you can check the angles with the numerical values unique to smartphones. Since the ruler display and mark display can be switched according to the purpose and preference, you can use it with your own easy-to-use appearance. Also, you can change the color freely