Today I’m building a standalone ESP32-S3 fingerprint attendance / check-in system that works completely offline. The whole idea is simple: one ESP32-S3 handles fingerprint verification, on-screen feedback, keypad input, and logging to an SD card—no computer, no cloud, no server. I’m using an FPM11A green-light optical fingerprint sensor over UART (pins 16/17), and the nice part is the ESP32 never sees raw fingerprint data—only a template ID and confidence score—so it’s a better fit for classrooms or group projects where privacy matters. For the UI, I’m using a 1.8” ST7735 TFT (SPI) to show status, scan results, usernames, and timestamps in real time. The SD card stores everything locally as CSV so you can open it straight in Excel, and I pull names from a simple users.csv file on the card (I made a list of 20 random names in Notepad and dropped it in the root). The firmware has two modes: verify mode for fast check-ins triggered by the sensor touch pin, and admin mode where a 4x4 keypad lets me enroll, delete, or count templates by ID without reflashing. I only use Wi‑Fi in the background to sync time so the timestamps are accurate.