  The production of numerical relativity waveforms that describe quasicircular
binary black hole mergers requires high-quality initial data, and an algorithm
to iteratively reduce residual eccentricity. To date, these tools remain closed
source, or in commercial software that prevents their use in high performance
computing platforms. To address these limitations, and to ensure that the
broader numerical relativity community has access to these tools, herein we
provide all the required elements to produce high-quality numerical relativity
simulations in supercomputer platforms, namely: open source parameter files to
numerical simulate spinning black hole binaries with asymmetric mass-ratios;
open source $\texttt{Python}$ tools to produce high-quality initial data for
numerical relativity simulations of spinning black hole binaries on
quasi-circular orbits; open source $\texttt{Python}$ tools for eccentricity
reduction, both as stand-alone software and deployed in the $\texttt{Einstein
Toolkit}$'s software infrastructure. This open source toolkit fills in a
critical void in the literature at a time when numerical relativity has an ever
increasing role in the study and interpretation of gravitational wave sources.
As part of our community building efforts, and to streamline and accelerate the
use of these resources, we provide tutorials that describe, step by step, how
to obtain and use these open source numerical relativity tools.
