Help and contact
The questions that come up most often
These are the questions we hear most. If yours isn't here, or something isn't working the way it should, just write to us — the address is at the bottom of this page.
Why does Vumble need location all the time?
Because Vumble recognises your trips without a start button. Without background access you would have to tap start before every journey — which is exactly what the app is meant to spare you. Your location never leaves your device.
Where is my data kept?
Everything stays locally on your device. There is no account, no server, no advertising and no analytics. The app makes no network requests. There is more on this in the privacy policy.
Why are kilometres sometimes missing?
Vumble would rather count too little than too much. Measurement noise is discarded rather than counted, which is why very short trips don't show up at all. On a bike ride, the first few minutes can also be missing.
What makes a day count towards the streak?
A day counts when Vumble reached at least energy level 1 and the app was opened that day. Opening it matters because movement is recorded in the background but only evaluated when you open the app. Days can be credited up to seven days afterwards — so if you cycle on Monday and only look in again on Wednesday, you don't lose the Monday.
Where do the CO₂ figures come from?
For cars, buses and trains, from the emission factors of the German Environment Agency (Umweltbundesamt, TREMOD 6.71B, reference year 2024), given in grams of CO₂ equivalent per passenger-kilometre. The figure for e-scooters is our own estimate, because the Umweltbundesamt does not cover them in that comparison.
Vumble asks which vehicle I was in — why?
Because automatic detection can only tell that you are in a vehicle, not which one. A bus, a train and a car all feel the same to a phone, but they differ considerably in CO₂ compared to driving. If you don't answer, the trip is counted as a car. On request the app remembers your answer for the same route and won't ask again next time.
Still stuck?
Write to info@vumble.de. The more precisely you describe what happened and on which device, the better the chances of tracking down the cause.