Hi HN,I built a simple, single-purpose iOS utility: a bubble level that lets you calibrate out the physical angle offset caused by iPhone camera bumps and cases. It automatically switch between 3 modes when you try to use it on the back, along the long edge, or along the short edge.The Problem with the iPhone s Measure app and other Bubble Level apps:If you lay a modern iPhone flat on its back to see if a surface is level, the camera bump (and the shape of the phone case) tilts the device by a degree or two. Existing apps do not offer a correct way to calibrate this physical offset away, and are often annoys you with Ads, paywall, etc. Their so called calibration allow you to click a button to set the reading to zero, but when you rotate your phone on the same flat surface, it won t be zero anymore. The correct calibrated reading should be zero no matter how you place the phone.The Solution:I wanted a clean tool that solves this specific issue. To use it, you place your phone on a known flat surface, tap Zero and follow the instruction to simply rotate your phone a few times. Now you can use your iPhone as a leveler as if it has a flat case.A Few Details:- Free: The calibration feature is free to use, a one time payment of $1.99 to enable sub-digit reading and haptic/sound feedback. - Privacy: The app collects zero user data and requires no sign-ups or network permissions. - UI: It is designed to be minimal and lightweight, focusing only on the utility of leveling.The app is free to download: https://apps.apple.com/us/app/id6767735397I would appreciate your feedback on the usability, the calibration flow, or any additional utility features you think would be useful to add.Thanks!