Calibrew: Coffee Dial-In

Calibrew is a dial-in coach for home coffee. You brew, tap how the cup tasted, and it changes one thing for the next cup. Since only one thing moves between cups, you can tell what made the difference.

YOUR MACHINE Calibrew starts with what you brew on. The change it suggests depends on the machine:

• On a bean-to-cup machine it moves the grind one setting at a time, only while the grinder runs, and waits for the third cup to judge it. After the grind comes strength, then cup size. • With a pressurised basket the grind barely shows in the cup, so it changes the dose. • On a lever or hand pump, your kettle sets the temperature and the way you pull does the pre-infusion. • On a heat exchanger it asks for a cooling flush before it blames the grinder for a bitter shot. • With a dual boiler or pressure profiling, it can also change the temperature and the peak pressure. • For filter and immersion it works with the drawdown, the bloom and the grind, and leaves espresso's rules out. • Moka pots, capsules and Turkish coffee get a direct fix for the cup instead of a dial-in loop.

THE COFFEE Type the name on the bag or scan its label. Calibrew recognises 41 origins, 143 growing regions, 12 processes and 30 varieties, and "About this coffee" tells you what to expect in the cup and what that means for your recipe. A dense Kenyan wants more heat; a natural wants a few more days of rest. It gives amounts in grams of your own dose, so there's no ratio to work out.

THE BAG Each bag keeps its own history, so Calibrew can see what a single tasting can't. When cup 2 was sour and cup 3 bitter, it tells you: "Cup 2 sour, cup 3 bitter — we stepped over it." If the grind has moved and the taste hasn't, it tries the next setting your machine has.

YOUR GEAR Calibrew's catalogue lists 570 espresso machines and brewers, 260 grinders and 71 scales. They are models sold in Europe, the US and Turkey over the last ten years, entered with their real grind ranges, basket sizes and boiler types.

LABEL SCANNING Frame the bag and press the shutter: Calibrew reads the coffee's name, the roaster, the process, the tasting notes and the roast. Your iPhone reads the photo itself, and it never leaves the phone. You can also say it: tell Calibrew the coffee out loud and the same fields fill in.

THE LOG Calibrew saves every brew with what went in and how it tasted. As a bag dials in, its cups move toward the middle of a taste compass, and you can score a cup on the SCA form if you want a number.

AROUND YOUR DAY The brew you're making shows on the Lock Screen and in the Dynamic Island, and widgets show today's caffeine and your water. Caffeine and water can go to Apple Health.

FOR TWO If you brew for someone else too, they get their own recipe and favourite bags, and their caffeine doesn't count toward yours.

LANGUAGES You can use the app in English, Deutsch, Español, Français, 日本語, 한국어 or Türkçe, and the coach reads bag labels written in any of them.

PRIVACY Your log stays on your iPhone. You don't need an account, and there are no ads or tracking. After setup, Calibrew asks once whether you'd like to share your brews anonymously to help the coach learn: it would send recipes, gear models and the type of coffee, while your name and anything you type stay on the phone. Sharing stays off unless you turn it on. You can export the whole log as a file, or delete everything from Profile.

Discovery signals