Loading…
Your AI endurance coach
Kalle is a science-based AI coach that plans, adapts and analyzes your training every day, so every hour you put in moves you closer to your goal. Built for athletes with ambition. Free.
Plugs into the gear you already train with
Kalle reads your wellness and activity data live through intervals.icu, from Garmin, Wahoo, Coros, Apple Watch, Suunto and the rest.
Your coach
Most training plans are generic and frozen. Kalle is neither. He learns your physiology, your goals and your life, then prescribes the exact session you are ready for today, with the reasoning behind it. Ambition, coached at your own pace, without waiting on someone who never has time.
Why today
You are fresh and recovering well, so we lift your sustainable ceiling. Hold the watts steady through each block; resist the urge to surge.
No spreadsheets, no guesswork. Three steps from signing up to a session with a reason behind it.
Link intervals.icu once. Kalle pulls your HRV, sleep, resting HR and every activity automatically.
Your zones, sports mix, goals and constraints, plus what you tell him, become a model of you that sharpens with every session.
Every morning, a session built for today with the physiology spelled out. Do it, adapt it, or ask him why.
Always on
Travel, a rough night, a tight calf, a meeting that ate your evening. Message Kalle like you would text a coach and he reflows today and the rest of the week on the spot. No guilt, no rigid plan you quietly abandon.
Multi-sport
Cycling, running, swimming, trail, ski-mountaineering, biathlon, strength, you name it. Set your sport mix, your off-days and how long you like to go, and Kalle coaches the whole athlete, not one slice of you.
Rigorous by design
Kalle reasons in 7-zone power and 5-zone heart-rate models, respects the power-duration curve, and is fluent in modern methods like Norwegian double-threshold. Every prescription names the physiological system it targets and why it fits today's HRV, sleep and load, powered by Anthropic's latest models.
See how zones work →Pricing
Kalle is free. It is built by one athlete who wanted a coach that actually adapts. If it makes your training better you can buy me a coffee, but you never have to.
Yes. No trial, no credit card, no paywall. There is an optional tip jar if you want to support it.
Kalle is best with a connected device through intervals.icu (free), but you can also just tell him what you did and he will coach from that.
Endurance and strength: cycling, running, swimming, trail, ski-mountaineering, biathlon, rowing, strength and more. Set a mix and he coaches them together.
Your training data stays yours. API keys are encrypted at rest, never shared, and never sent to your browser.
A plan is fixed; Kalle is a coach. He re-decides every day from your real data and adapts the moment life changes.
Your most personalized season starts today. Free.