TechCrunch reports that between them Levchin and Birch have invested around $500,000, adding to the small amount of seed funding Mixpanel had already secured from early-stage venture capital firm Y-Combinator.

Mixpanel differentiates itself from packages like Google Analytics in that its focus is on measuring how users engage with site applications, such as games, and other activities such as photo sharing, commenting, tweeting and watching videos, rather than reporting raw site traffic numbers.

The company was co-founded by Tim Trefren and Suhail Doshi.