The Sourdough Sidekick, a kitchen appliance developed by FirstBuild and King Arthur Flour, is priced at $179.99 and sold in the United States. It is designed to automate the feeding of a sourdough starter, a task that traditionally requires regular manual addition of flour and water.

The device accepts a 15 g starter and stores flour and water in separate containers. It offers three modes: Auto, which schedules feedings based on a user‑set bake date and ambient temperature; Ratio, which provides preset flour‑to‑water ratios and allows setting starter weight and feed frequency; and Custom, which lets users define seed amount, feed intervals, and exact flour and water quantities for each feed.

Auto mode limits the minimum output to 150 g for intervals of a few days and to 400 g for periods of four days or longer, which can generate more discard than manual feeding. It also restricts bake planning to dates within the next week. The crock and lid are not dishwasher safe and must be hand washed, while the water tank and flour hopper are dishwasher safe. The unit operates a stirring cycle roughly every two hours, producing audible noise.

Testing with white flour showed the starter remained active and produced a loaf, though the loaf was overproofed. The device handled most whole‑wheat and rye flours, but coarse rye flour required manual adjustment of water content. FirstBuild recommends cleaning the glass crock, lid, and paddle after each feeding cycle. The Sourdough Sidekick may be most suitable for users with larger kitchens who bake at least twice weekly; for smaller kitchens or less frequent bakers, its single‑purpose design and counter‑space requirements may limit utility.