Skillwise
DBT Diary Card
Health
Cold Plunge, Sauna
A timer and journal for cold plunges, saunas, and the contrast between them
Contrastly is a timer and journal for cold plunges, saunas, and contrast therapy, built for anyone who wants to track sessions and see patterns over time. It’s an iPhone app made by Develak.
Screenshots
Overview
Most trackers ask you to remember what you did and type it in after the fact. Contrastly times it while it happens, both the cold and the heat, so the record matches what you actually did rather than what you recall later.
Beyond the timer, Contrastly works with Apple Health, offers guided protocols for cold, heat, and contrast, and shows weekly, monthly, and yearly trends for time, temperature, and tolerance. Sessions can carry a photo, a note, and how they felt, and your journal can sync privately or export to CSV.
Contrastly is a timer and a journal for cold plunges, saunas, and the contrast between them.
Most trackers ask you to remember what you did and type it in afterwards. Contrastly times it while it happens — the cold and the heat — and keeps the record so you can look back at what you actually did.
Logging is never paywalled. Unlimited sessions, the start/stop timer for cold, heat, and contrast, your history, and your streak are all free, forever.
Contrastly Pro adds every guided protocol, Health correlations, trends, presets, photos, private iCloud sync, widgets, and full export. Monthly and annual subscriptions are available, and the annual plan starts with seven days free. A one-time lifetime purchase is also available.
Subscriptions renew automatically unless cancelled at least 24 hours before the end of the current period. You can manage or cancel in your App Store account settings.
Contrastly is a journal and a timer. It gives no medical advice and makes no health claims. Cold and heat exposure carry real risks, including cold shock and heart rhythm disturbances. Never go alone, get out whenever you want to, and talk to a doctor before you start.
Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Privacy Policy: https://develak.com/privacy-policy/
Highlights
Contrastly times cold plunges, saunas, and contrast sessions, then tracks trends, Apple Health data, and your history in one journal for iPhone.
Cold, heat, or contrast sessions start with a single tap, with no form to fill in first.
Cold is tracked as a full session here, not just a checkbox on a sauna entry.
Progressive programs for cold, heat, and contrast start at thirty seconds, and stopping early is always fine.
Sessions are written as workouts, and the heart rate already recorded while a session was running is shown alongside it.
Weekly, monthly, and yearly trends track time, temperature, and tolerance.
Your journal can sync privately across devices via iCloud and export to CSV.
Who it’s for
Anyone who steps into cold water regularly and wants a real timed record of each session rather than a note typed in afterward.
People who track heat sessions, including humidity settings up to 100 percent for steam rooms.
Anyone alternating between cold and heat who wants both halves timed and logged together.
People who prefer a guided, progressive program for cold, heat, or contrast exposure rather than freeform sessions.
Anyone who wants their cold and heat sessions to appear alongside the rest of their Health data.
How it works
From “Start a session” to “Sync and export”, in 5 steps.
Tap once to begin a cold, heat, or contrast session, with no form to fill in first.
Rounds, phase changes, and haptic cues mark every thirty seconds, with spoken guidance along the way, so you can put the phone down.
After a session, add a photo, a note, or how it felt, and it’s saved to your journal.
Open the weekly, monthly, or yearly trends to see how your time, temperature, and tolerance change.
With “Pro”, your journal syncs privately across devices via iCloud, and you can export your full history to CSV.
In depth
Contrastly reads the wall clock rather than relying on the screen staying awake, so a session stays accurate even if the screen locks or the phone is set down on a bench.
Rounds, phase changes, and haptic cues mark every thirty seconds, and spoken guidance in your language plays along the way, ducking your music instead of stopping it, so you don’t need to watch the screen.
With your permission, Contrastly writes sessions to Health as workouts. A workout is the only thing it writes.
The heart rate already recorded while a session was running is read back and shown alongside it, and sleep, resting heart rate, and heart rate variability are also read so you can see how exposure lines up with recovery. Nothing is written without your permission, and you can revoke access at any time.
The guided protocols are progressive programs for cold, for heat, and for contrast, starting at thirty seconds. A step counts once you have actually done it, not once you remember to log it afterward, and every step is a suggestion: stopping early is always fine, and nothing here asks you to beat a record.
Release notes
Version
1.0
This is the first version of Contrastly, released on August 18, 2026.
FAQ
Something else? The Contrastly support page covers purchases, sync and settings, and lets you write to us directly.
Yes. Contrastly is free to download from the App Store. Optional in-app purchases unlock extra features; they are billed by Apple to your Apple Account, and you can manage them at any time in your account settings.
Contrastly works on iPhone and iPad with iOS 17.0 or later.
Contrastly times both halves of a session, cold and heat, and keeps a record of duration and temperature, along with any photo or note you add and how the session felt.
Yes. Contrastly reads the wall clock, so a session stays accurate even if the screen locks or the phone is left on a bench.
They are progressive programs for cold, heat, and contrast that start at thirty seconds. A step counts once you have actually done it, and stopping early is always fine.
With your permission, Contrastly writes sessions to Health as workouts and reads back the heart rate already recorded while a session was running. It also reads sleep, resting heart rate, and heart rate variability so you can see how exposure lines up with recovery. Nothing is written without your permission, and you can revoke it at any time.
Yes. You can save presets for the temperatures, durations, and humidity you use every week, with humidity settings up to 100 percent for steam rooms.
You can export to CSV. The free plan exports your last 30 days, and “Pro” exports your whole journal.
Contrastly is available in 44 languages: Arabic, Bangla, Catalan, Chinese (Simplified), Chinese (Traditional), Croatian, Czech, Danish, Dutch, English, Finnish, French, German, Greek, Gujarati, Hebrew, Hindi, Hungarian, Indonesian, Italian, Japanese, Kannada, Korean, Malay, Malayalam, Marathi, Norwegian Bokmål, Odia, Polish, Portuguese, Punjabi, Romanian, Russian, Slovak, Slovenian, Spanish, Swedish, Tamil, Telugu, Thai, Turkish, Ukrainian, Urdu and Vietnamese.
Visit the Contrastly support page: it answers common questions about purchases, sync and settings, and has a contact form. You can also write to contact@develak.com. We read every message and reply personally.
Made by Develak
We design and build native iPhone, iPad and Mac apps for founders and companies, with the same care we put into our own. Tell us about your idea.