MathKey 1.1 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The actual developer of this Mac application is MathKey. The program lies within Productivity Tools, more precisely Office Tools.
From the developer:
MathKey converts your handwriting to LaTeX, MathML, or images. Therefore, the utility can convert your writing into a LaTeX/MathML expression suitable for Pages, Numbers, Word, and any compatible app. This way, you can add math expressions to your documents just by drawing them. You can just tap the image output to share and save it.
You may want to check out more software for Mac, such as Instant PDF, Simply Notes or Padre, which might be similar to MathKey.