The Web Edition is a free version with a limited set of supported devices compared to the Subscription Edition. Quartus II Software version 8.1 Release Notes - Intel
While the software is no longer supported by Intel, its release as a completely free, no-license-required tool ensures it remains accessible forever. Use the Intel official archives first. If that fails, exercise caution with community-sourced versions. Altera Quartus II 8.1 Web Edition -Windows- free download
: The software was not designed for Windows 7, 8, 10, or 11. While some users report successful installation on newer Windows versions using compatibility mode, this is not officially supported and may lead to unexpected issues. The Web Edition is a free version with
At least 1 GB of RAM is required for the stand-alone programmer, though more is recommended for complex design processing. Device Support (Web Edition) At least 1 GB of RAM is required