The source code is in https://github.com/beast-dev/tracer and is dependent on a library in https://github.com/beast-dev/beast-mcmc.
Rambaut A, Drummond AJ, Xie D, Baele G and Suchard MA (2018) Posterior summarisation in Bayesian phylogenetics using Tracer 1.7. Systematic Biology. syy032. https://doi.org/10.1093/sysbio/syy032