I just use an excel spread sheet on my laptop.....don't need to 'sync' with anyone tho.
Don't have any mobile devices, can't afford them, and get many distinct impressions that many apps lack a lot.
Nice because you can build the SS to do what you want, add to it, modify it.
Have many worksheets within to keep all kind of notes and references, daily egg count, and sales sheets calculate sales vs feed costs.