Your heat map, and everyone else’s

Your own heat map is local. It is drawn from the activities on your own phone and from nothing else, it needs no account, and nothing about it is uploaded. That is the layer that is always there.

On top of it sits the community layer, which shows where people actually run and ride. It is off until you turn it on, and displaying it is a separate switch from contributing to it — you can look without adding anything.

We said for a long time that we would not ship a community heat map until it could be done without collecting everybody's raw traces. This is what that turned out to require. A contributing activity sends which ~75-metre squares it crossed and in which week, as whole numbers: no coordinates, no time of day, no account, and the first and last 300 metres dropped so neither end of your route is in it. The label attached rotates every Monday, so two weeks cannot be tied back to one person. A path is drawn only once at least three different people crossed it in the same week — below three, nothing appears, which is what stops one person's route from being visible.

The honest cost: because a contribution carries no identifier, we cannot go back and find yours. Turning contribution off stops anything further being sent, and that is the whole of what it can do; what was already sent is deleted automatically within 26 weeks. The privacy choices page says the same thing in more detail.

The free heat map covers the last 30 days of your activity, and the free tier keeps one saved route. Premium extends the map to your whole history and lifts the route limit, along with every analytics chart and race predictions.

Deleting an activity removes it from the heat map. Your history is yours to prune.