caberQU

Smart USB-C Cable Tester

Most USB-C cables look identical, but two cables that look the same can behave completely differently: one might charge a laptop at 100W and carry a 40Gbit/s video signal, while the other, despite the same connector, is limited to charging a phone. Without a tester, the only way to find out is to plug it in and see what fails.

caberQU, a hardware startup from Linz, Austria, builds a handheld device that plugs into both ends of a USB-C cable and reads out its actual capabilities: supported USB modes, charging power, data speed, Thunderbolt and DisplayPort support, and the identity chip ("eMarker") built into higher-end cables. AppJoy developed the companion app for it.

The app connects to the caberQU device over Bluetooth Low Energy, pulls the raw diagnostic data it measures, and turns it into a report anyone can read at a glance: gauges for data speed and charging power, a cable health score, and a full breakdown of every USB mode, voltage, and current the cable supports. Every measurement is saved to a local history, so cables can be labeled, compared, and looked up again later.

Customer Benefits

• Native iOS and Android app, paired with the caberQU hardware over Bluetooth Low Energy
• Instant readout of data speed, charging power, and cable health, presented as simple gauges anyone can understand
• Full protocol breakdown: USB modes, Power Delivery profiles, Thunderbolt, DisplayPort, and eMarker chip data for cables that carry one
• Local history of past measurements to track and compare cables over time
• Over-the-air firmware updates for the connected device, delivered straight from the app
• Direct link to buy a matching cable when a tested one falls short

Implementation

AppJoy built the app from scratch as a native Flutter application for iOS and Android, in close collaboration with caberQU on how the device communicates over Bluetooth.

The caberQU device exposes its measurements as raw Bluetooth characteristics: comma-separated data on cable wiring, USB modes, and the eMarker chip. The app decodes these streams in real time as a cable is connected, cross-references them against caberQU's backend for the full spec breakdown, and only unlocks the results once every required reading has come in.

On top of the core measurement flow, AppJoy implemented the firmware-update mechanism that keeps deployed devices current, and the local history with CSV export for sharing results.