Download of TreeAnnotator 1.8 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. The software belongs to Productivity Tools. The actual developer of this free software for Mac is Andrew Rambaut, Alexei J. Drummond.
From the developer:
TreeAnnotator is a program for summarizing the information in a sample of trees. The summary information includes the posterior probabilities of the nodes in the target tree, the posterior estimates and HPD limits of the node heights and (in the case of a relaxed molecular clock model) the rates.
You may want to check out more software for Mac, such as svgo-gui, Logic Server or Random Decision Maker, which might be related to TreeAnnotator.