Download of YubiKey Personalization Tool 3.1.25 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The software lies within System Tools, more precisely Device Assistants.
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 software for Mac is Yubico. The most popular versions among the application users are 3.1 and 3.0.
From the developer:
Graphical personalization tool for YubiKey tokens.
YubiKeys are USB tokens that act like keyboards and generate one-time passwords, static passwords or work in challenge-response mode.
This is a graphical tool to customize the token with your own cryptographic key and options.
You may want to check out more software for Mac, such as FLIR Tools, Smart Screen Tool - Capture Video or Chaikin Power Tools, which might be similar to YubiKey Personalization Tool.
Device Assistants
Device Assistants