I've been hatching eggs for a couple years and never found a tracking method I actually stuck with — mix of a notebook, phone reminders, and just trying to remember when lockdown was supposed to start. Eventually I just built something for myself: set2pip.com
It logs egg batches separately, counts down to lockdown and hatch day, and keeps a record of temp/humidity readings so I can actually look back at what happened during a hatch instead of guessing. No cost, no account required unless you want your data synced across devices.
Mainly built it to solve my own problem, but figured it might be useful to others here too. Still actively working on it, so if you run into something broken or missing, I'd genuinely like to hear about it.
Set2Pip