While Yosemite 10.10.5 is stable, it is no longer receiving security patches from Apple. If you plan to use this OS for daily tasks involving sensitive data, ensure you use a modern, third-party browser like Firefox (Legacy version) or Chromium-based alternatives that still support older macOS versions. This will help mitigate risks associated with outdated system security.
For a safe download, avoid third-party "DMG" links found on search engines, as they often contain adware. Use the official Apple Support link to download the installer App, and use the Terminal command if you require bootable media. mac os x yosemite 1010 5 download dmg link
The official way to download OS X Yosemite 10.10.5 is through Apple Support While Yosemite 10
If you need a bootable disk image (DMG/ISO) for a virtual machine or an older Mac, you must convert the official App using Terminal. For a safe download, avoid third-party "DMG" links
OS X Yosemite 10.10.5 Download DMG Link If you need to download the file, you can get it directly from Apple. This version, released on August 13, 2015, is the final stable update for Yosemite and is known for introducing a modern, flat design inspired by iOS. Official Download Links
Once installed, update to 10.10.5 Combo Update (if needed) and consider disabling Gatekeeper for legacy apps. Enjoy the flat design, continuity features, and rock-solid stability of one of Apple’s finest vintage operating systems.