Health

Contrastly

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.

Age
4+ years old
Category
Health & Fitness
Price
Free In-app purchases
Languages
44 EN · FR +42
Requires
iOS 17+ iPhone · iPad
Size
10.3 MB
Version
1.0

Overview

What is Contrastly?

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.

Read the full App Store description

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.

Start, don’t type

  • One tap starts a cold, heat, or contrast session. No form to fill in first.
  • Both halves are timed. Cold is a real session here, not a checkbox on a sauna entry.
  • Rounds, phase changes, and haptic cues at every thirty seconds, so you can put the phone down.
  • Spoken guidance in your language, ducking your music instead of stopping it.
  • The clock is read from the wall clock, so a session stays accurate even if the screen locks or you leave the phone on a bench.

Apple Health that actually works

  • Sessions are written to Health as workouts, so they appear alongside the rest of your activity.
  • The heart rate already recorded while a session was running is read back and shown alongside it. A workout is the only thing Contrastly writes.
  • Sleep, resting heart rate, and heart rate variability are read so you can see how exposure lines up with recovery.
  • Nothing is written without your permission, and you can revoke it at any time.

Guided protocols

  • Progressive programmes for cold, for heat, and for contrast, starting at thirty seconds.
  • A step counts when you have actually done it — not when you remember to fill in a form afterwards.
  • Every step is a suggestion. Stopping early is always fine, and nothing here asks you to beat a record.

See the pattern

  • Weekly, monthly, and yearly trends for time, temperature, and tolerance.
  • Presets for the temperatures, durations, and humidity you use every week — humidity up to 100%, because steam rooms exist.
  • Session photos, notes, and how each one felt.

Yours, and portable

  • Private iCloud sync across your devices.
  • CSV export: your last 30 days free, your whole journal with Pro. Your records leave with you.
  • CSV import, free on every plan. Bring a journal in from another app or an old phone.
  • Home Screen and Lock Screen widgets.

Free and Pro

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.

A note on safety

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

What can you do with Contrastly?

Contrastly times cold plunges, saunas, and contrast sessions, then tracks trends, Apple Health data, and your history in one journal for iPhone.

One tap starts a session

Cold, heat, or contrast sessions start with a single tap, with no form to fill in first.

  • Both halves are timed

    Cold is tracked as a full session here, not just a checkbox on a sauna entry.

  • Guided protocols

    Progressive programs for cold, heat, and contrast start at thirty seconds, and stopping early is always fine.

  • Works with Apple Health

    Sessions are written as workouts, and the heart rate already recorded while a session was running is shown alongside it.

  • See the pattern

    Weekly, monthly, and yearly trends track time, temperature, and tolerance.

  • Private sync and export

    Your journal can sync privately across devices via iCloud and export to CSV.

Who it’s for

Who is Contrastly for?

  • People who do cold plunges

    Anyone who steps into cold water regularly and wants a real timed record of each session rather than a note typed in afterward.

  • Sauna and steam room regulars

    People who track heat sessions, including humidity settings up to 100 percent for steam rooms.

  • Contrast therapy practitioners

    Anyone alternating between cold and heat who wants both halves timed and logged together.

  • Anyone following a structured protocol

    People who prefer a guided, progressive program for cold, heat, or contrast exposure rather than freeform sessions.

  • Apple Health users

    Anyone who wants their cold and heat sessions to appear alongside the rest of their Health data.

How it works

How does Contrastly work?

From “Start a session” to “Sync and export”, in 5 steps.

  1. Start a session

    Tap once to begin a cold, heat, or contrast session, with no form to fill in first.

  2. Let the app keep time

    Rounds, phase changes, and haptic cues mark every thirty seconds, with spoken guidance along the way, so you can put the phone down.

  3. Add what happened

    After a session, add a photo, a note, or how it felt, and it’s saved to your journal.

  4. Check the trend

    Open the weekly, monthly, or yearly trends to see how your time, temperature, and tolerance change.

  5. Sync and export

    With “Pro”, your journal syncs privately across devices via iCloud, and you can export your full history to CSV.

In depth

Contrastly, in detail

How does Contrastly time a cold plunge or sauna session?

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.

How does Contrastly work with Apple Health?

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.

What do the guided protocols in Contrastly look like?

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

What’s new in Contrastly

Version

1.0

This is the first version of Contrastly, released on August 18, 2026.

Is Contrastly free?

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.

Which devices does Contrastly work on?

Contrastly works on iPhone and iPad with iOS 17.0 or later.

What does Contrastly track for a cold plunge or sauna session?

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.

Does the timer keep running if my phone locks or I set it down?

Yes. Contrastly reads the wall clock, so a session stays accurate even if the screen locks or the phone is left on a bench.

What are the guided protocols in Contrastly?

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.

How does Contrastly use Apple Health?

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.

Can I set my own presets for temperature, duration, and humidity?

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.

Can I export my Contrastly journal?

You can export to CSV. The free plan exports your last 30 days, and “Pro” exports your whole journal.

What languages is Contrastly available in?

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.

How do I get help with Contrastly?

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

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