PHITER
Beta · By invitation
PHITER.ai

The AI coach that thinks like a sports scientist.

Trains you like an athlete, not a user. Reads your sleep, fuel, fatigue, and PRs — then changes tomorrow's plan accordingly. In any language you speak.

No credit card · Cancel anytime

Today's Plan
Push A · 7 lifts
Calories
2,450 / 3,000
Streak 🔥
21 days
10:42 ●●●● ●● 82%
Phit
Good morning.
🔥 21
stuck at 315 squat. 6 weeks no PR.
your weekly squat volume is averaging 9 sets — a stalled lifter needs 14–18 to drive new growth.
adding 2 working sets at RPE 7 from Monday. re-test week 3.
Push A · Monday +2 sets
Squat6 × 5
Bench4 × 5
RDL3 × 8
Vault updated
2,108
/ 2,840 kcal
Today · 74%
Protein
156 / 200g
Carbs
182 / 280g
Fat
62 / 88g
Today
🍳Eggs & oats
540
🥗Chicken salad
420
🍱Chicken & rice bowl
+620
Updated by Phit
M
P
T
L
W
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F
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Push A
~52 min · RPE 7
1
Back squat
3 min rest · was 4×5
6 × 5 · 315
2
Bench press
3 min rest
4 × 5 · 225
3
Romanian deadlift
2 min rest
3 × 8 · 185
4
Overhead press
2 min rest
3 × 8 · 95
Message Phit…
PHIT
Command
Fuel
Perf
Profile
Three things, done right

Decisions.
Not data.

Most fitness apps drown you in graphs. PHITER gives you the next move.

Phit knows you. By name.

Your PRs. Your recovery. Your goals. Your last shoulder tweak. Phit holds all of it — and brings it up the moment it matters. A sports scientist with the warmth of a training partner.

Programs that change with you.

Strength, hypertrophy, cardio, bodyweight. Each plan is generated from real periodization rules — not pulled from a template library — and rebuilt as your data shifts.

Sees, scores, adjusts.

Send a video — get bar path and tempo. Snap a meal — get macros logged. Skip a session — tomorrow's plan adapts. Phit watches everything and folds it into the next decision.

Why PHITER

Real science.
Not vibes.

Every plan, every meal, every cue traces to peer-reviewed exercise science — the principles elite coaches actually use.

How Phit actually thinks

Other AI fitness apps generate plans by asking ChatGPT "make me a workout." Phit doesn't work that way.

Underneath every Phit response is a deterministic science engine built on decades of research — Schoenfeld's hypertrophy meta-analyses, Israetel's volume landmarks, Seiler's polarized cardio model, Mifflin-St Jeor metabolic equations. The AI talks to you. The engine makes the call.

That's why your plan adapts to your sleep. Why injuries auto-substitute exercises. Why a bad week dials volume down without you asking. It's not magic — it's math, validated by sports science.

"Every human body is an adaptive biological system. It responds to stress by becoming more capable of handling that stress — the universal law underlying all training."
1
Calories from your physiologyMifflin-St Jeor formula — the gold standard in clinical nutrition. Calculated from your weight, height, age, gender, and activity. Not "average male" guesses.
2
Volume that actually worksPer-muscle weekly set targets between Minimum Effective Volume and Maximum Recoverable Volume — the science-validated zone for hypertrophy and strength.
3
Cardio the right way80% Zone 2, 20% Zone 5 — the polarized model used by elite endurance athletes. No more useless steady-state hours.
4
Injuries respectedKnee, shoulder, low-back, wrist — every pattern has safe substitutions baked in. No "consult your doctor" disclaimers. Real biomechanics-aware swaps.
5
Periodization that breathesAccumulation, intensification, deload — your training cycles automatically. Bad week? Phase resets. Strong week? Volume escalates.
6
Recovery as a signalSleep hours, readiness, and adherence aren't decorations. They directly modify tomorrow's plan. Phit treats recovery like a coach does — as data.
How it works

Three minutes to your
first session.

1

No forms. Just talk.

Phit asks about your goal, your level, your equipment, your injuries. You answer like you would a coach. Done in 3 minutes — not 30.

2

Your week, programmed.

Phit hands you a full training week + nutrition targets, built from your data alone. Not a template. Not a generic split.

3

Train. Adapt. Grow.

Phit checks in daily, adjusts loads, watches your videos, logs your meals — and answers anything, in your language.

Built different

What only Phit can do.

No comparisons, no chest-thumping. Just what makes Phit a different category of coach.

Native in
English

A coach that doesn't translate — it thinks in your language. Hebrew, Spanish, German, Mandarin, Arabic, Portuguese. Same depth, same nuance, every time.

A real science engine.
Not an AI improvising.

Every workout traces to peer-reviewed periodization rules — MEV, MAV, MRV volume landmarks, polarized cardio, phase-based progression. Phit can't invent a plan. The engine generates it. Phit explains it.

One conversation.
Whole system updates.

Tell Phit you switched to keto. Your calorie ring re-targets. Your meal plan rebuilds. Your training adapts to the lower carb day. No menus, no settings — just talk.

Form analysis from a video.
Bar path, tempo, joint angles.

Upload one bench press from your phone. Get back biomechanical scoring + 3 cues to fix. Powered by frame-by-frame video analysis.

🍱
P
C
F

Photo a meal.
Macros in 2 seconds.

Snap your plate. Get calories, protein, carbs, fat — logged. No database to search, no portion estimating. The vision model does it.

Remembers everything.
Forever.

Your bench PR from six months ago. The shoulder you tweaked in May. Your preference for morning lifts. Phit doesn't forget — and brings it up only when it matters.

Voice coaching mid-set.
Hands-free.

Don't put down the bar. Just talk. Phit answers out loud through your earbuds while you're between sets — no screen-tapping with chalky hands.

Knows your body's limits.
Substitutes intelligently.

Tweaked your back? Phit swaps the deadlift for trap-bar. Bad shoulder? Floor press instead of bench. Biomechanics-aware substitutions, not random alternatives.

REST
GO

Reads your readiness daily.
Plan adapts on its own.

Slept 4 hours? Heavy day moves to Friday. Crushed last session? Plan pushes harder. Phit watches your sleep, fuel, fatigue, and PRs — and adjusts before you ask.

Pricing

Simple. Honest.
No surprises.

Start free. Upgrade when you want. Cancel anytime — actually anytime.

Free
$0/forever
See if Phit clicks. No credit card.
  • 5 Phit messages per day
  • 1 training plan per week
  • Workout logging + PR tracking
  • Basic food logging
  • Form analysis (Pro only)
  • Unlimited Phit chat (Pro only)
Get started
Questions

What you're probably wondering.

Is Phit just ChatGPT in a wrapper?+
No. Phit runs on Claude with a deterministic science engine controlling every training plan. The real difference is what Phit remembers: your PRs, your sleep last night, the shoulder you tweaked in May, the diet switch you made last week, your readiness this morning, the form cues from your last video, your fatigue, your meals, your streak. Phit folds all of it into tomorrow's plan — every day. ChatGPT starts every conversation from zero. Phit doesn't.
What makes Phit different from other fitness apps?+
Most fitness apps either lock you to templates (Fitbod, Strong) or sell you a human coach (Caliber, Future) at $30+/mo. PHITER is the AI version of an elite coach — conversational, adaptive, grounded in real exercise science — at $19.99/mo. And it's the only one fluent in your language, whatever your language is.
Can I cancel anytime?+
Yes. One click. No "are you sure?" screens, no retention calls. Cancel and you keep access until the end of your billing period.
Does it actually adapt to my training?+
Yes. Every session you log, every meal, every readiness check feeds back. Bad week? Plan dials back. PR week? Plan pushes harder. The same logic an elite coach uses — automated.
What about my data?+
Your training data is yours. Encrypted at rest, never sold, never used to train external AI models. Delete your account and everything goes with it — usually within 24 hours. Full details in our Privacy Policy.
I'm a beginner — is this overkill?+
No — it's the opposite. Beginners benefit most because the engine routes them past the usual first-year mistakes (too much volume, wrong exercises, no recovery). You don't need to know what "MEV" means — Phit handles the science, you just train.
Why no Apple Watch app yet?+
Coming. Native iOS + Android apps with Apple Health and Health Connect are in active development. The web app works on mobile today — same product.

Stop guessing.
Start training.

Seven days, free. No credit card. Cancel in two clicks if Phit isn't the coach you wanted.