Greek yogurtsingle cup
9.2 / 10
Onyx: Fitness & AI Coach
For iPhone and Apple Watch
Fitness that
knows you.
Onyx reads your watch, your bloodwork, your training, and your food. Then it tells you the one thing to do today. And why.
82
Readiness · Primed
−3.1
years, biological age
55 g
protein to go today
Most fitness apps give you more numbers to figure out. Onyx gives you an answer. One sentence. One button. And the reason behind both.
Readiness
Wake up knowing.
While you slept, Onyx read your heart rate variability, resting heart rate, sleep, and breathing. It turned them into one simple score, measured against your own body. Not a stranger's average.
Try it. Drag the sliders. Illustrative, not medical advice.
Green means push. Red means rest. The gym will still be there tomorrow.
Early warning
It notices before you do.
Some mornings your signals drift together. Resting heart rate up, HRV down, temperature a touch high. Onyx spots the pattern, shows you exactly what it is seeing, and eases your week until you are back at baseline.
Tap Recovery Mode and watch your week ease off.
No black box. Every call comes with its reasons. A heads-up, never a diagnosis.
Coach
Just ask.
Coach knows your last workout, your last meal, and last night's sleep, because it's all connected. Ask a question and get an answer that's actually about you. Ask for a plan and Coach builds it. Nothing changes until you tap approve.
And yes, Coach has a face now. Make it yours. Change the mood, the colour, the outfit. It reacts to what you do.
Bloodwork
Your labs, in plain English.
Take a photo of your lab report, or import the PDF. Onyx reads every marker, charts it against its range, and keeps track across every draw. Your bloodwork finally becomes something you can use. Not something you file away.
Illustrative values.
- Explained simplyWhat each marker means, and why it matters to your energy, recovery and training.
- Acted on, gentlyIron running low? Onyx eases your training and points you to iron-rich food. LDL high? More fibre, worked into your week.
- Tracked over timeWatch a marker move from draw to draw, and see your habits working.
- First report freeImport your most recent labs and see what they've been trying to tell you.
Fuel
Food that fits your body.
Scan a barcode, snap a plate, or just say what you ate. Every food gets two scores. One for the product. And one for you, today, based on your bloodwork, your readiness, and your training.
Same shelf. Two different answers.
A food can be fine in general and wrong for you today. Flip the switch and watch the verdicts change.
Instant ramenone pack
1.8 / 10
Almond butterper 2 tablespoons
6.9 / 10
Illustrative examples. In the app, both scores come from the real product and your real data.
Training
Training that meets you where you are.
Some mornings you're primed. Some mornings you barely slept. Onyx re-reads your recovery before it writes your workout, building across 4-to-8-week blocks that grow, peak, and ease off. Just like a good coach would plan them.
Tap a circle to finish a set.
Logging is one tap. Your numbers are already there, filled in from last session. Between sets, a calm timer counts you back in.
Illustrative run. Routes and heart rate come from your Apple Watch.
Runs, walks, and rides track live: pace, splits, heart-rate zones, your route drawing itself. And your Watch can run a whole session without your phone. Leave it in your bag.
Body
See the whole picture.
Eight simple domains. Vitals, sleep, fitness, nutrition, movement, and more, gathered into one calm view of how you're doing. Plus a biological age that shows, honestly, how your habits are adding up.
What if… Move a habit and watch the years respond. Illustrative, an estimate, not a medical test.
Your readiness lives where you already look. Lock Screen, Home Screen, and your Watch face. One glance, and you know what kind of day it's going to be.
Sleep
Sleep, explained.
A score of 97 is nice. Knowing why is better. Onyx breaks down your night, deep, REM, core and awake, and Coach tells you what to repeat tonight.
Illustrative night.
Your week
Progress you can see. A week already planned.
Every Monday, your week in review: sessions, volume, sleep, and how it compares to last week. And every session is built the night before, so tomorrow is never a question.
5sessions+1 on last week
79.2klb lifted+8% volume
81avg sleep score+3
3day streakkeep it going
Mon
Tue
Wed
Thu
Fri
Sat
Sun
For real life
Bodies change. Your plan should, too.
Maybe you're on a GLP-1, and your appetite isn't what it was. Maybe you're coming back from a hard month, or a hard year. Onyx doesn't hold you to a plan written for who you were. It reads who you are this week: protein that protects your muscle, training that bends instead of breaking, labs that show what's really changing. No guilt. Just guidance.
Privacy
Your health belongs to you.
📱
On your iPhone
Your scores, trends and plans are worked out on your device. Your body is not a cloud dashboard.
🔒
Asked, then minimal
Coach asks before anything is sent to its AI, and then sends only what's needed, never your name. Your health data stays out of iCloud.
🚫
Never sold
Your health data is never sold, never used for ads, and never used to train AI. That's the whole idea, in one line.
Pricing
Free where it counts.
Everything your iPhone works out on its own is free. Pro is simply the part that thinks with you.
Onyx
Free
$0 · no card to start
- Readiness score & illness early-warning
- The adaptive training program & Recovery Mode
- Session grades, cardio load & biological age
- Both scores on every food
- Your first bloodwork report
- Widgets for Lock Screen, Home Screen & Watch
Onyx Pro
Coach, unlimited
$29.99 / year · a free week, where available
- Coach, unlimited: questions, programs, meal plans
- Unlimited meal logging by photo or description
- The meal planner & menu reading
- Every bloodwork report after your first
- Monthly and lifetime options, too
Subscriptions renew automatically unless cancelled at least 24 hours before the end of the period, and are managed in your Apple ID settings.
Questions
A few things people ask
What do I need to use Onyx?
An iPhone running iOS 26. An Apple Watch brings the full picture: overnight HRV, resting heart rate, sleep, and wrist temperature feed your readiness score and the early warning. And it can run your workouts all on its own. Onyx has a proper iPad layout, too.
What's actually free?
A lot: readiness and the illness early-warning in full, session grades, cardio load, biological age, sleep need and debt, the adaptive program, Recovery Mode, both food scores, and your first lab report. Pro ($29.99 a year, free week where available) adds Coach unlimited, unlimited photo and description meal logging, the meal planner, menu reading, and unlimited lab reports.
How does the bloodwork part work?
Photograph a report or import the PDF. Onyx charts every marker against its range, tracks it across draws, explains it in plain language, and turns anything flagged into a gentle suggestion, always as a card you approve. It's a heads-up, not a diagnosis.
Where does my health data go?
Your scores, trends and plans are computed on your iPhone, and your health data isn't stored in iCloud. When Coach or a photo needs a larger AI model, Onyx asks first, then sends only what's needed, without your name. Your health data is never sold, never used for ads, and never used to train AI. The privacy policy has every detail.
I'm on a GLP-1. Is Onyx for me?
Very much so. Your appetite, recovery, and labs are all changing at once, and Onyx reads all three: protein targets that protect your muscle, training that adapts day by day, and bloodwork tracked over time so you can see what's really happening.
Is Onyx a medical device?
No. Onyx is not a medical device and does not diagnose. It offers a heads-up and a plan for the day. Please talk to your doctor about your results.
Say hello to Onyx.
Download it free tonight. Wake up tomorrow to one clear answer, and find out what your body has been trying to tell you.
Point your iPhone camera here.