bunchr is an R package for bunching analysis. It also includes bunchApp, an interactive simulator for exploring bunching and elasticity estimation. Bunching is a phenomenon where many individuals self select to a specific point in the range of some variable (e.g. earnings) because of some incentive discontinuity (e.g. marginal tax rate change). In such case, a histogram will show a “bunch” - observable excess mass otherwise unexpected - at that point. In economic literature, it is used to recognize a behavioral response to change in incentives, and estimate structural parameters (e.g. elasticity of earnings w.r.t. marginal tax rate).