The 3.1 version of GFXBench for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The program lies within System Tools, more precisely Benchmark. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The actual developer of this free Mac application is Kishonti Ltd.
From the developer:
GFXBench is a comprehensive cross-platform and cross-API 3D graphics benchmark that measures graphics performance, long-term performance stability, render quality, and battery. You can compare your results with all the other uploaded results inside the app on the Compare Page. On the Info Tab, you can review the hardware and graphics capabilities of your device.
You may want to check out more software for Mac, such as GFXBench Metal, which might be related to GFXBench.
Benchmark