ESP32 Compatible RTC Sensors

If you just want the time to be right, the DS3231 is the answer: its temperature-compensated crystal drifts by minutes per year rather than per month, it runs on 3.3V I2C, and modules usually include the backup coin cell holder. The PCF8563 is a leaner low-power I2C alternative when board space or current budget is tight.

The DS1307 and DS1302 date from the 5V Arduino era - they work, and the pages here show the wiring that makes them behave at ESP32 voltages, but there is little reason to design them into something new. Whichever chip you use, the battery keeps time through power cuts; the ESP32 then syncs from it at boot instead of needing Wi-Fi and NTP.