Hello HN,

I’m the developer behind Tooliz. I built this because I was frustrated with the current state of utility apps on the Play Store—most are either 100MB+ bloatware, require unnecessary permissions (like contacts/location for a flashlight), or force full-screen video ads just to use a simple ruler.

I wanted to build a single, lightweight app that respects the user and focuses on UI/UX efficiency.

The Tech Stack: It’s built with Flutter. I chose it to handle the custom painting required for the tools smoothly at 60fps+ on both Android and iOS.

Interesting Technical Challenges:

The Radial Menu: I didn't want a standard grid or drawer. I implemented a custom Radial Menu using CustomPainter and heavy trigonometry to handle the touch hit-testing and animations. It feels much faster for thumb navigation than reaching for a top-left hamburger menu.

Sensor Fusion & Hardware:

Metal Detector: Accesses the raw magnetometer stream (sensors_plus package). I had to implement a calibration step to filter out the background magnetic field and isolate local anomalies (metals).

Sound Meter: Uses the microphone stream to calculate decibels. Mapping the raw PCM data to accurate dB SPL values across different device microphones was... painful. I used a calibration offset system to mitigate hardware variance.

Offline-First Architecture: Except for a minimal ad banner (to keep the project alive), everything works offline. For the Unit Converter, I hardcoded the conversion logic instead of relying on an API, so it works instantly in airplane mode.

Monetization: It’s free. There is a small banner ad (AdMob) at the bottom.

I’d love to hear your feedback on the Radial UI implementation or the sensor accuracy on your specific device!