How to count the Omer
Count each night from after Pesach until the eve of Shavuot: a blessing, then the day’s number. The siddur has a dedicated Omer page. The count is done at night, after nightfall, with a blessing and then the day’s formula. If you forgot at night, later days have special rules about the blessing — follow your community’s custom. On the Omer page in the siddur you can read the order on your phone.
Is there an app page?
Yes. The siddur has a dedicated Omer URL.