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Washed coffees peak around day seven, naturals around day eleven — day nine is the rounded default the app is named for. It's a name, not a law — every coffee is different, which is why the app tracks your specific bag rather than telling you to always wait nine days. The full schedule is in our science of coffee freshness .

That's the whole point. Most coffee tastes harsh and gassy in the first few days after roast — the CO2 hasn't off-gassed yet and the flavors haven't settled. day9 is telling you to wait. Depending on the bean, peak flavor usually arrives somewhere between days 7 and 14.

Yes for tracking and viewing your bags. The roaster directory and any features that pull live data need a connection, but logging brews and seeing your freshness curve work without one.

Open the app, go to Settings, tap "Delete account." Your bags, brews, and data are removed within 24 hours. If you can't access the app for some reason, email us from the address on the account and we'll handle it.

Yes. day9 doesn't sell data, doesn't share it with advertisers, and doesn't have advertisers. Full details are in our privacy policy, linked at the bottom of this page.

iPhone (iOS 16+) and Android (7+ / API 23+). Download from the App Store or Google Play . You can also use day9 in your browser at app.day9.coffee .