Shopify discount codes and automatic discounts have start and end dates, but in most themes they only show in the cart and at checkout, not as a crossed-out sale price on the product page. For a visible sale price you have to change the product price itself, and Shopify cannot schedule that.
Good when a checkout discount is enough. Set start and end dates under Discounts. The product page still shows the full price.
Set compare-at price to the current price and lower the price, then reverse it when the sale ends. This works for a handful of products and fails at scale: someone has to be awake at the end time, and without a record of every original price, mistakes stay.
SaleGuard sets a start and end time for a price-based sale, records every original price first, checks every change landed, and restores every price exactly at the end time with nobody watching.
Instilus apps · Built by Instilus, a trading name of A Star Supply.