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Built for serious runners·5K · 10K · Half · Marathon

Plans that knowhow you actually run.

An adaptive training plan from 5K to marathon, with an AI coach on every session and the pro-grade metrics — CTL/ATL, VO₂max, race predictions — most apps lock behind premium pricing.

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9:41
TodayThursday · 21
Form+12
RunLive

Easy run · 8 km

Aerobic, flat, HR zone 2.

Distance8,0km
Pace5:42/km
Heart142bpm
This week4 sessions
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18
T
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W
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21
F
22
S
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24
Briefing

Easy aerobic, zone 2. Yesterday's load was high — keep it light.

Apple Health · Garmin · FIT · GPX

Apple HealthHealth ConnectGarminSuuntoCOROSPolarWahooFIT · GPX · TCXApple HealthHealth ConnectGarminSuuntoCOROSPolarWahooFIT · GPX · TCX
What sets ONSLF apart

Three things the others get wrong.

Adaptive plans

Plans that follow your actual training — not the other way around.

Every day is calibrated from what you really ran. Missed sessions reshuffle, hard weeks back off automatically, and the taper executes itself in the final weeks before your race.

What's inside
Physiology

Form, fitness, risk — the way pros read it.

CTL, ATL, TSB, VO₂max and race predictions from 5K to marathon. Recovery from HRV, sleep and resting heart rate. Read like a sentence, with confidence levels — never a black box.

What's inside
Routes

New routes, described in words.

Tell the AI "flat, 8 km, shaded along the river" and get a GPX route, ready for your watch. Or take an old run and turn it into a public route — with surface analysis and an elevation profile.

What's inside
Personalized plans

Pick a finish line. We build the weeks.

Every plan adapts to the runs you actually do — missed sessions reshuffle, hard weeks back off, and the taper executes itself before race day.

Everything in one app

What else you get.

A training product only works when the data is trustworthy, the guidance is explainable, and the workflow is fast on mobile.

Official sync paths

Apple Health, Health Connect, Garmin Developer, Strava OAuth, plus FIT / GPX / TCX upload. Every source stays tagged on the workout — no anonymized data blob.

Briefing

Easy aerobic, zone 2. Yesterday's load was high — keep it light.

68%

AI coach with guardrails

A short briefing on every session, grounded in your real training. No medical claims, no silent auto-adjustments — you stay in control.

5:42min/km

iOS, Android, Watch

Native iPhone and Android apps; push to Apple Watch and Wear OS. Offline recording, then clean sync.

Clubs, events & challenges

Training groups, group runs, monthly challenges that don't punish rest days. Public, private or club-only.

Data sovereignty

Your data stays yours.

Other platforms lock your history behind a premium tier. Here, recording, importing and exporting are free — regardless of what you subscribe to.

Privacy zones for GPS

When a workout starts or ends near a place you'd rather not pin, the GPS trace fuzzes at exactly that spot.

Addresses encrypted

Privacy-sensitive locations are stored so even our team can't read them.

Full export, anytime

FIT, GPX, TCX, CSV, JSON, or a single ZIP with everything. No lock-in, no waiting, no premium paywall.

Plus, done fairly

Pay for coaching. Not for basic rights.

Recording, importing and exporting are free. Plus unlocks the active training — not access to your own data.

ONSLF PlusMost picked
This weekAdaptive plans
Mo
18
Di
19
Mi
20
Do
21
Fr
22
Sa
23
So
24
Briefing

Easy aerobic, zone 2. Yesterday's load was high — keep it light.

+12Fresh · Fitness +3

Active training, unlocked.

  • AI coach on every session
  • Adaptive training plans with B-race support
  • Create routes and generate them with AI
  • Submit segment efforts and chase leaderboards
Start trainingFree to install. No tracker, no ad SDK.
Free · €0
ONSLF Plus
  • Host clubs, run events, create challenges
  • Capture territory with your club
Free
  • Record and import workouts
  • Full export: FIT, GPX, TCX, CSV, JSON
  • Privacy zones and encrypted addresses
  • Personal records and history
  • Attend events, join challenges
Why runners switch

Built for runners who already track everything.

Finally an app that respects the data I've spent five years collecting. Imported my history, generated a plan that matched my fitness within a week.

Beta testerMarathon · 3:14
01 / 03

The AI briefing actually tells me why a session is what it is. Most apps just hand me a number and a colour code.

Beta testerHalf marathon · 1:28
02 / 03

Privacy zones, full export, no premium paywall on my own data. That alone was enough to switch.

Beta tester10K · 38:40
03 / 03
Ready

Start today. Run better today.

Bring your workout history with you. We'll turn it into your first plan.

Free to install. No tracker, no ad SDK.