The same two drinks hit
two people differently.
Jjan understands your body and your condition, and looks after both.
One color while you drink, personalized hangover care the next morning — and it gets more accurate the more you use it.
Free · iPhone & Android · 5 languages (English, Korean, Japanese, Chinese, Spanish)
No numbers, just 🟢🟡🔴.
and it sharpens as you log.
when your liver clocks out.
without a lecture.
Mom calls. (Not really.)
Not tracking — understanding
Plenty of apps count your drinks. Jjan takes that count and estimates how buzzed you are right now. Sex, age, build, your usual tolerance, whether you flush — even how fast soju hits compared to beer — all folded into a buzz curve that's yours alone. And the answer isn't a number. It's a quiet green, yellow, or red light.
Right beside you, all night
If your pace picks up, Jjan gives you a gentle nudge. It reminds you to drink water, and lets you log a drink with one tap from the lock screen — no need to even open your phone. Widgets and Live Activities keep it with you the whole night. And if you go past the number you set, nothing scolds you — instead you'll see how many sessions in a row you've kept to your plan.
⌚️ One tap from your wrist
With an Apple Watch you never have to reach for your phone. Add a drink or a glass of water right from your wrist — and start a quiet exit there too. Premium feature.
Still there the next morning
The morning report replays last night in a voice that never judges — when the drinks bunched up, whether you stayed in the green. Then it asks how you're feeling. The more you answer, the better Jjan reads you. Go Premium and you also get personalized hangover care tuned to last night's total and this morning's condition, plus a liver recovery timer — see right on your home screen when your liver clocks out, and over time, discover your own hangover patterns.
🌏 Speaks 5 languages
English, Korean, Japanese, Chinese (Simplified), and Spanish — the entire app, from widgets and lock screen to insight articles, follows your language setting. And in case you were wondering about the name: Jjan — it's what Koreans say when glasses clink. Cheers, basically.
🔬 The research behind it
Jjan's buzz engine is built directly on the numbers from 16 peer-reviewed medical studies and drinking guidelines from around the world. A few highlights —
· Body-composition regression for alcohol distribution (Seidl, Int J Legal Med 2000 · 529 subjects)
· Total body water formulas (Watson, Am J Clin Nutr 1980 · 723 subjects)
· Measured absorption rates by drink type — why wine and soju hit faster than beer, drink for drink (Mitchell, ACER 2014)
· Alcohol flush (ALDH2) prevalence in Korea and what it means (JMIR 2024, among others)
There are lots of drinking apps. None of them do the math like this. That's why Jjan's lights are calibrated to your body — not somebody else's average. The full receipts are here.
One thing, honestly — buzz estimates are for reference only. Jjan never gives you a verdict or a score, and it must never be used to decide whether you can drive. Please only use Jjan if you're of legal drinking age.
Jjan doesn't track you. Your drink records live only in your own iCloud — we can't see them. To improve the app we receive only anonymous, aggregate usage stats (which screens get used), with no record contents and no advertising ID. Without Premium you'll occasionally see an ad (your first session is ad-free), but it's non-personalized — never targeted tracking. Go Premium and there are no ads at all.
The Quiet Exit
Stuck at a table you can't gracefully leave? Tap one button, and 30 seconds later your lock screen rings. Answer it, and the voice you picked comes through — "Where ARE you? Get back here, now" — and all you have to do is stand up looking suitably apologetic.
Set the caller name, ringtone, and timing in advance — or record your own voice. Everything happens right on your phone. No one actually gets called. Ever.
Starting tonight: good nights, lighter mornings.