Looking for plugin for users to select shifts to work

We need a calendar / scheduling plugin that would allow workers to sign up for shifts. Can anyone recommend something like that (free or paid).

My idea is that the administrator would designate the available time slots and job openings. For example:

Cashier: Monday-Friday 8am – 6pm, Saturday 7am – 5pm.
Cook: Monday-Friday 6am – 8pm, Saturday 5am – 8pm.
Cleaner: Monday-Friday 9pm – midnight, Sunday noon-6pm.

Then workers would fill in their name for the days/times when they can work.

Ideally the workers would be able to use a front-end calendar to see the current schedule and sign up for shifts.

Any plugins like that available?