Stillcraft / Apps / Temper
A smith tempers steel with fire and water: heat it, quench it, again and again, until it holds an edge. You can temper yourself the same way. Temper is a timer, a guide and a ledger for cold showers, ice baths, open water, contrast showers and the sauna. Every session folds a new Damascus layer into your own blade: it glows after practice and gathers frost when you stop. No ads, no account, no internet access.
Android 8.0+ · Free · Works offline · English & Русский
A shower, a bath, open water or an ice hole. A minute of calm breathing on land, a target time, then a voice through the shock, the settling and the calm. A cautious limit set by the water temperature, and afterwards you warm up on your own.
Leave the phone outside the shower: a voice and tones call "hot" and "cold". Five programs from Gentle start to Steel, or your own, and the last round always ends on cold.
The phone can't come in, so it doesn't have to. Before you go in it tells you the clock time to come out and rings every minute after. Tap "I'm out" and it leads the plunge and the rest. Finnish sauna, banya, hammam or infrared, and Søberg's "end on cold".
Each session folds a Damascus layer: cold ones dark, hot ones bright. The hamon deepens with your chain, the spine takes on eight temper colours from raw iron to steel grey as you level up, and you can share the blade as a picture.
11 minutes of cold and 57 of heat a week after Søberg's 2021 study, a gentler goal, or your own, and a chain of practice days that one rest day doesn't break. Before each session: "how much do you not want to?" from 1 to 5. Watch it fall over the weeks, with energy and mood after.
24 maker's marks and five trials: First Ice takes you from 15 seconds to 3 minutes over 30 sessions, then Dawn, Contrast fortnight, Eight saunas and Wild water. 12 articles, from the first 30 seconds to the banya, and safety first.
| Program | Heat | Cool | Rest |
|---|---|---|---|
| First visits | 2 × 8 min | 1:00 | 10 min |
| Finnish classic | 3 × 12 min | 2:00 | 10 min |
| Russian banya | 3 × 10 min | 1:00 | 12 min |
| Søberg | 3 × 15 min | 2:00 | 5 min; the last round ends on cold |
| Hammam | 3 × 15 min | 2:00 | 10 min |
On Xiaomi (MIUI / HyperOS), Huawei, Samsung and some other phones, allow Autostart for Temper and remove battery limits so a session keeps running and the sauna clock rings with the screen off.
JDK 17+ (Android Studio's bundled JBR works) and the Android SDK.
git clone https://github.com/bigdevwhale/temper.git cd temper ./gradlew testDebugUnitTest # unit tests ./gradlew assembleDebug # debug APK ./gradlew installDebug -Pdemo # app.temper.demo with ten weeks of made-up sessions
Cold water and heat are real strain on the heart. If you have heart disease, high or low blood pressure, an arrhythmia, Raynaud's or epilepsy, are pregnant or unwell, ask a doctor first. Never go into open water alone, never hold your breath in water, and get out at once if you feel chest pain, dizziness or numbness. The app's limits are cautious guides, not a promise.
Phones don't like water or a sauna's heat, and you shouldn't be looking at a screen in either. Temper speaks and rings instead, and in the sauna it tells you the clock time to come out before you go in.
They come from Susanna Søberg's 2021 study of winter swimmers who also used the sauna: about 11 minutes of cold and 57 of heat a week, spread over several sessions. You can pick a gentler goal or set your own.
Settings → Backup saves every session, mark and trial into one JSON file. Restore it on the new phone.
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Found a bug, missing a feature, or want it in your language? Tell us on GitHub.
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