Real-time caffeine metabolism curve and bedtime estimate
Stimly models estimated caffeine levels over time. Inputs: drink logs, body profile, and a short calibration quiz. The system renders a live clearance curve, distinguishes slow sipping from fast intake, tracks tolerance trends, and shows estimated caffeine remaining at bedtime.
Hi, I'm Mateusz, a solo developer from Poland.
I drink a lot of coffee and yerba mate, and the caffeine trackers I tried treated every cup like a light switch: one dose in, simple exponential decay out. That never sat right with me.
So I went down the rabbit hole and spent a lot of time reading absorption kinetics papers and prototyping models. The model I kept simulates caffeine moving from your gut into your bloodstream, and out again as your body clears it. It spreads each drink over the time you take to finish it (a Bateman infusion model), so a cold brew sipped over two hours rises slower and peaks later than an espresso finished in seconds. Lattes, energy drinks, and teas each get their own absorption profile too. Your personal half-life comes from a short quiz on how coffee affects you, adjusted for age and factors like smoking or hormonal contraception.
Still it's an estimate, not a lab test. But it's the closest I could get to what that 3 PM coffee is doing in our bodies.
A few things it does:
- Shows estimated caffeine levels now, the projected peak, and how much may remain at bedtime.
- Estimates baseline tolerance after three days of logging.
- Lets you log body signals like focus or jitters and see them on the curve.
Everything above is free. PRO adds 90-day history, tolerance trend charts, an expert brewing mode, and a 30-day PDF export.
If you track caffeine or care about sleep timing: does the curve line up with how you actually feel? I'm most interested in the days it doesn't ;)
About Stimly on Product Hunt
“Real-time caffeine metabolism curve and bedtime estimate”
Stimly launched on Product Hunt on September 25th, 2026 and earned 59 upvotes and 1 comments, placing #48 on the daily leaderboard. Stimly models estimated caffeine levels over time. Inputs: drink logs, body profile, and a short calibration quiz. The system renders a live clearance curve, distinguishes slow sipping from fast intake, tracks tolerance trends, and shows estimated caffeine remaining at bedtime.
On the analytics side, Stimly competes within iOS, Health & Fitness, Coffee and Vercel Day — topics that collectively have 222.5k followers on Product Hunt. The dashboard above tracks how Stimly performed against the three products that launched closest to it on the same day.
Who hunted Stimly?
Stimly was hunted by Mateusz. A “hunter” on Product Hunt is the community member who submits a product to the platform — uploading the images, the link, and tagging the makers behind it. Hunters typically write the first comment explaining why a product is worth attention, and their followers are notified the moment they post. Around 79% of featured launches on Product Hunt are self-hunted by their makers, but a well-known hunter still acts as a signal of quality to the rest of the community. See the full all-time top hunters leaderboard to discover who is shaping the Product Hunt ecosystem.
For a complete overview of Stimly including community comment highlights and product details, visit the product overview.
Mateusz