Kissmetrics doesn't offer a free tier (they have a 14 day free trial but after that all customers have to commit to an annual contract). Mixpanel does have a fr

Kissmetrics doesn't offer a free tier (they have a 14 day free trial but after that all customers have to commit to an annual contract). Mixpanel does have a free tier. Full disclosure – I'm a founder at Heap, which is a competitor to both of these products. We do offer a free tier as well.