Organic electrochemical transistors (OECTs) have emerged as a next-generation biosensing technology because of their water-stability, cost-effectiveness, and ability to obtain high sensitivity at low operation voltage (mV). However, a miniaturized readout unit that can wirelessly characterize the overall performance of an OECT is still missing, which hinders the assembling of truly wearable OECT systems for continuous health-monitoring applications. In this work, we present a coin-sized analytical unit for remote and wireless OECT characterization, namely, a personalized electronic reader for electrochemical transistors (PERfECT). It has been verified that PERfECT can measure the transfer, output, hysteresis, and transient behavior of OECTs with resolution and sampling rate on par with the bulky equipment used in laboratories. PERfECT is also capable of characterizing other low-voltage transistors. An integrated board for multiplexed OECT characterizations (32 channels) has also been demonstrated. This work provides a missing building block for developing next-generation OECT-based bioelectronics for digital wearable applications.