Krauseler has unveiled the Muxcard, a credit-card-sized computer prototype. The device fits in a wallet and runs on an ESP32-C3 microcontroller.
Muxcard features ESP32-C3 and ePaper display
The Muxcard features a 1.54-inch 200×200 flexible ePaper display with partial update support. It includes an RC522 NFC read/write module, a LIS2DW12 accelerometer, and a 30mAh rechargeable LiPo battery. The prototype is 1mm thick, slightly above the ISO/IEC 7810 ID-1 standard of 0.76mm.
Specifications
- MCU: ESP32-C3 (RISC-V, Wi-Fi, 320KB SRAM, 384KB ROM)
- Display: 1.54-inch 200×200 flexible ePaper with partial update
- NFC: RC522 read/write module
- IMU: LIS2DW12 accelerometer
- Battery: 30mAh rechargeable LiPo, 1mm thick

Krauseler plans to add USB Type-C, a microSD slot, touch buttons, and a thinner battery in future versions.
The creator said that holding a device that feels like a normal card while seeing the screen update still feels surreal. Krauseler has not confirmed a release date or pricing for the Muxcard.

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