01
Your history is scattered across tools
A streak in one app, a mood note in another, and your health metrics somewhere else. When the context is split, it's hard to see what the last two weeks actually looked like.
BY DAY
0
Stop guessing what actually improves your health.
You've tried the tips, the supplements, and the routines. Some of them may have helped, but without structure and real before-and-after data, you still do not know what actually worked. By Day helps you test one change at a time and see the result clearly.
- One change at a time
- Real health data, not guesswork
- See results in 7-21 days
Create your account during open beta and start seeing progress before May 5, 2026.
Start trackingPrefer mobile? Download the app below.
- No credit card required
- Private by default
- Works on web and mobile
Open beta ends on May 5, 2026. Already have an account? Sign in.
Sound familiar?
You've tried everything. You just don't know what worked.
Cold showers. Magnesium. Screen curfews. Walking 10k steps. You stuck with it for a couple weeks and then... was your sleep actually better? Was it the supplement or the routine? You're not lazy. You just never had a way to close the loop.
02
How you felt disappears unless you log it
Wearables miss part of the picture, and memory rewrites the rest. You need a quick daily check-in that sits next to the objective signals instead of replacing them.
03
Most dashboards stop at charts
Seeing a trend is not the same as knowing what to do next. You need the app to turn your recent sprint data into a clear signal you can keep, drop, or test again.
Here's how By Day works
One goal. One sprint. Real answers.
A sprint is a focused 7-21 day program with a daily checklist and health tracking built in. Browse the catalogue, pick a proven program, and follow it through with clear daily structure and progress.
01
Pick a sprint from the catalogue
Start with a proven program for sleep, focus, energy, or stress. Browse the catalogue, preview the structure, and choose the sprint that fits your goal.
02
Follow a daily plan
Each day gives you 3-6 focused tasks, 10-30 minutes. No guessing. The plan is built, the order is set, every step has a reason.
03
Track what actually changes
Connect Apple Health or Oura to see real metrics move: sleep, HRV, resting heart rate, activity. No wearable? Track how you feel instead.
04
Keep what works. Drop what doesn't.
Review how your recent averages changed, keep the habits that helped, and use that signal to decide what to keep or test next.
Join beta
Run guided health experiments free during beta.
Create your account now and use the dashboard, guided sprints, and health tracking while beta is open.
See every experiment in one place
Review your sprint, your progress, and your health trends together so patterns are easier to spot.
Start with a focused plan, not another tip list
Pick a goal like sleep, focus, energy, or stress and get a plan built for testing one change at a time.
See what actually changed
Track mood, habits, and connected health data together so you can stop guessing and learn faster.
See it in action
Your dashboard for every experiment
See daily tasks, health trends, and before-and-after results across every sprint. Mobile stays in sync for day-to-day follow-through.
Starter experiments
Start with a proven program.
Not sure where to begin? These experiments are pre-designed and evidence-backed. Pick one, run it for 7-21 days, and see the results. Then choose your next sprint with better context.
Goal
Cadence
Intensity
Sprint pages
Learn more about each sprint before you get started.
Why it works
Cleaner experiments. Clearer answers.
By Day gives you a defined sprint window, objective health signals, and a clear next step after every test.
01
A defined test window
A sprint gives you a clean 7-21 day window to test one change without muddying the results with five others.
02
Your body becomes the feedback loop
Sleep, HRV, resting heart rate, and consistency turn 'I think it is working' into signals you can actually trust.
03
The next experiment gets smarter
Instead of starting from scratch, you finish each sprint with a clearer next move: keep, drop, or test.
Join beta
Start your first sprint and see what actually changes.
During beta, the dashboard, guided sprints, and health tracking are included, so you can start a sprint, connect your data, and see what changed before subscriptions begin. Open beta runs through May 5, 2026.
Step 1
Create your account
Create a new account during open beta and everything you need to run your first sprint is ready right away.
Step 2
Complete your first tracked sprint
Finish your first sprint during beta and, if you are among the first 200 to finish, you keep the full version for life.
Live now
Premium
During beta, this includes dashboard access, guided sprints, and health tracking. Finish your first sprint early enough and you keep the full version for life.
0 of 200 lifetime premium spots claimed
During beta Free Every new account gets dashboard access, guided sprints, and health tracking during open beta.
After beta ends
$8.99 /month
$84 /year
Save $23.88 versus monthly
- Guided sprints + premium sprint catalog
- Apple Health + Oura integration
- Health trends + before-and-after results
- Experiment history across web and mobile
- One account across web and mobile
After beta ends, anyone who did not earn one of the first 200 lifetime spots moves back to free unless they subscribe.
FAQ
Questions about experiments, data, and access
Everything you need to know before you start your first sprint and begin tracking what changes.
Seeing this page as a health data tracker.