Sometimes you need more than a standard vesting schedule with evenly spaced vesting tranches, like the common 4-year vest with 1-year cliff. Captable.io supports these custom vesting schedule:
Vesting with custom time-based tranches
Go to Company > Vesting & Departure

Click Add Custom Schedule

Vesting tranches can be divided by percentage and frequency:

The resulting stock option:

To represent upfront vesting, enter 0 month duration for the first tranche. The percentage in this 0-month tranche will vest on the vesting start date.