'NIMBLE' is a general purpose modeling framework that facilitates the analysis of Markov Chain Monte Carlo (MCMC) models. However, it constructs a complex and variable data structure, which is difficult to use in a general way. The 'nimbleExtra' package provides a set of functions to insulate users from the complexity and variability of 'NIMBLE' data structures. It also complements 'NIMBLE' and other MCMC analysis packages by providing missing functionality to encourage generic programming. Together these features ease the burden of working with MCMC data and encourage more systematic approaches to MCMC analysis.