Triathlon · Running · HYROX · iOS
Your race ahead.
Your training, today.
A clear workout for today. Your whole week at a glance. A training and fueling plan that adapts to what you actually did — with every change explained. Built for your race, and the life around it.
7-day free trial for eligible subscribers · then $9.99/month or $79.99/year · cancel in one tap · no ads, no data selling
Redesigned app · TestFlight preview
The problem
By week three, every static plan is a lie.
You have three sports, a job and a race on the calendar. Then you get sick, or a meeting eats Wednesday, or you sleep five hours three nights running. A PDF can't see any of that. It just keeps counting down while you fall behind a schedule that was never built for the week you actually had — and from then on you're patching it yourself.
Darwin's answer isn't to guilt you into catching up. It's to rebuild.
How it works
Three steps, then it runs itself.
Tell it your race
Distance, date, and the days you can actually train. Darwin builds a full week-by-week periodized plan to race day — and shapes sessions around the course you're really racing: climbing work for a hilly bike leg, heat-adapted sessions for a hot race, open-water skills if you're not swimming in a pool.
Just train
Completed workouts sync from Apple Health, along with sleep, resting heart rate and HRV. Nothing to log twice. Keep day notes alongside your sessions, and move workouts when life changes your schedule.
A new week, an updated plan
Open Darwin after a week ends and it reviews your completed training and recovery, then rebuilds the weeks ahead. Nail the week and it progresses you. Miss sessions or sleep badly and it pulls volume back and drops intensity, rather than pretending the week went fine.
The part worth being precise about
A deterministic engine. Not a chatbot.
Darwin never asks a language model how hard you should train. Every training-load decision comes from a rule-based engine — the same inputs always produce the same plan — with hard limits written into it and covered by tests.
A language model does exactly one job here: turning the engine's decisions into a paragraph you can read. It never makes them.
This is the app's central honesty claim. It is also why the plan can be trusted with a race you have been training eight months for.
Inside the app
Today. Your week. The work you’ve done.
A look at the redesigned Darwin experience. Screens shown from the latest TestFlight build; App Store availability may vary.
See your sessions and daily fuel tags together in one weekly calendar.
Open a completed workout to compare your recorded results with the original target.
See your monthly training totals, with your workout history one tap away.
Look back at the training you actually completed, synced from Apple Health.
Fueling
The part most apps leave to you.
Every long session carries a carbohydrate target in grams per hour. Every day is tagged low, medium or high carb based on the training you're actually doing that day — so a big Saturday is fed on Friday, not apologised for on Sunday.
- Session-level targets on the rides and runs long enough to need them
- Daily carb tags that move with your rebuilt week
- No second app and no calorie diary
Apple Health
Your data does the logging.
With your permission Darwin reads completed workouts, sleep, resting heart rate and heart rate variability from Apple Health, and factors them into the weekly rebuild. Garmin, Whoop, Oura, Coros and Apple Watch all write there already.
- Health data stays on your phone. Raw workouts, HR streams, sleep records and GPS routes are never uploaded.
- Darwin never writes anything back to Apple Health.
- Optional. Decline the permission and the app still works — you just tell it what you did.
Built for your race
Pick the event. Darwin builds the rest.
Triathlon
Ironman, 70.3, Olympic and sprint. Three sports balanced against each other, bricks paired properly, open-water work when the swim isn't in a pool.
Running
Marathon and half marathon, built around a long run that progresses honestly and a taper that doesn't collapse in the last fortnight.
HYROX
Eighteen HYROX events in the catalog, planned as one race: compromised running, the station work it demands, and strength that counts toward your load instead of hiding from it.
Course profiles are only used when they've been verified. A wrong elevation figure silently changes how you train, which is worse than no figure at all — so races without a confirmed profile simply don't show one.
Pricing
One plan. Every week to race day.
We warn you before the annual charge.
Start a trial on the annual plan and Darwin sends a notification three days before it converts, naming the date and the amount. Nobody makes us do that. We do it because being ambushed by a large renewal is the loudest complaint about every app in this category.
Why this exists
I wrote this after a very bad afternoon in Cambridge, Maryland.
Eagleman 70.3 was my first one. I went in less fit than I wanted to be and, worse, with my nutrition guessed rather than planned. My stomach turned on me early and the half marathon became a walk between portable toilets.
I'm a dad and a lawyer. Every app I tried wanted me to build my life around a training schedule, and none of them took fueling seriously. So I built the one that does both. Six weeks after I started, I raced a second 70.3 in Maine and took nearly 40 minutes off my time.
That's the whole reason the plan rebuilds instead of scolding, and the reason fueling is a first-class feature rather than an afterthought.
— Justin Ramirez, founder
Your race is on a date. Your life isn't.
Eligible subscribers get a 7-day free trial. Manage or cancel your subscription in your Apple account.
iPhone only · Apple Health optional · see the App Store listing for the iOS version required