A bio age you can argue with
13 domains, 100+ peer-reviewed coefficients, every threshold published. If you disagree with a number, you can read the paper it's based on.
iPhone · iOS 17+
Lower your bio age, daily.
Thier is a personal longevity coach. It reads your wearables, runs them through a transparent bio-age model, and tells you the one thing worth doing today — not 47 things.
What it is
A longevity stack you can actually live with.
Most health apps either drown you in metrics or flatten everything into wellness fluff. Thier sits in the middle: rigorous enough to take the data seriously, simple enough to use every morning.
A daily protocol that adapts
The five things to do today, weighted by what's drifting in your data. Not a static checklist — a feedback loop that gets less generic the more you use it.
An AI doctor that's read your data
A longevity-focused chat that already knows your bio age trend, sleep debt, last lab panel, and what you flagged in onboarding. No re-explaining yourself every session.
A library to make it stick
24 tracks across sleep, nutrition, movement, longevity drugs, peptides, and more. Short lessons, citations, quizzes, and a quote you can share when something clicks.
How it works
From "I wear a watch" to "I have a plan", in one sitting.
Sync your stack
HealthKit at the centre. Connect Oura, Garmin, Polar, Withings, Fitbit, or Strava in two taps. Manual entry for the things they don't measure (BP, body fat, lab values).
Get your bio age
A 13-domain physiological-age estimate, decomposed so you can see exactly which signals are pushing you up and which are pulling you down.
Work the next move
A daily protocol, a weekly focus, a doctor that remembers, and a learning track in the gap area. Built so showing up matters more than perfection.
Open math
Every coefficient is on the Science page.
13 domains, additively composed, capped per-domain. No black-box "wellness score" — every number maps to a line in the engine, anchored to a peer-reviewed source.
Read the science →
Real roadmap
Shipped, not promised.
7 wearables wired today (Apple Health, Oura, Garmin, Polar, Withings, Fitbit, Strava). AI doctor with memory. 24-track learning library. Peptides, polygenic risk, and family-history coaching are next.
See what's in the app →13
Bio-age domains modelled
100+
Peer-reviewed coefficients
24
Learning tracks
7
Wearables supported
Free · 30 seconds
Calculate your bio age
Same engine the app runs on real users. No signup. Get a number you can actually argue with.
Open the calculator → Free · interactiveRun a what-if scenario
Sleep an extra 30 minutes, walk 3,000 more steps, drop 2 kg. See how your bio age moves before you commit.
Try the simulator → Live · public feedSee what the community is doing
Posts on longevity, fitness, peptides, sleep hacks. Real people running their N=1.
Open the feed →
From early users
Built around what people actually do, every day.
A few words from the people running on Thier today.
"I've tried four longevity apps. This is the first one that gave me a number I could actually argue with — every coefficient is on the science page, line-anchored to a paper. That changed how I treat the bio age it gives me."
"The daily protocol is the bit that's actually changed my behaviour. Most apps give you twenty things to do. Thier gives me one move that's worth doing today, based on what my Oura and Apple Watch already saw."
"I'm a GP, and the thing that sold me is what Thier doesn't do. It doesn't pretend to diagnose. It doesn't push supplements. It tells me my VO₂ max trend, my HRV trend, and the move that nudges them — and it's right about both."
"I bought a Polar, an Oura ring, and a Withings scale and couldn't get a single coherent picture out of any of them. Thier sits on top of all three and gives me one bio age, one trajectory, one thing to do. That's what I was paying for and never getting."
FAQ
Questions worth answering up front.
Who is Thier for?
People who already track their health, read Attia / Huberman / Sinclair, and want a coherent system instead of seven app silos. People who'd rather work from a transparent bio-age model than a wellness score they can't audit.
Is the bio-age model open?
Yes. Every coefficient and threshold band lives on the Science page, line-anchored to the engine source code with the peer-reviewed paper inline. Disagree with a number? You can read the citation it's based on.
Which devices does it support?
iPhone with iOS 17 or later. HealthKit is the primary source. OAuth integrations: Oura, Garmin, Polar, Withings, Fitbit, Strava. Manual entry for everything else (BP, body fat %, lab values).
Will Thier replace my Oura / Garmin / Whoop app?
No. Thier reads from the apps you already use and turns those signals into a coherent daily plan. Your existing dashboards stay where they are.
How is my data handled?
Health data stays in HealthKit and your wearable provider's API; Thier reads it on demand. Account data lives in Supabase, encrypted at rest and in transit. Full details in the privacy policy.
Is there a free trial?
Yes, a 7-day free trial on every plan. Annual is the cheapest per-month, monthly is no-strings.
Add a year to your healthspan today.
Thier costs less than a single supplement bottle, and it's the one app on your phone whose job is to make the rest of your stack mean something.