Use archived/legacy official downloads:
The Altera (now Intel) Quartus II 8.1 Web Edition was a free, no-license-required version of the design software used for CPLD and medium-density FPGA development . Released around 2008, it originally targeted operating systems such as Windows XP and Windows 2000 . Altera Quartus II 8.1 Web Edition -Windows- free download
Unlike modern tools, Quartus II 8.1 Web Edition does not require internet activation. However, it requires a license file to enable the Web Edition features. However, it requires a license file to enable
While Intel (which acquired Altera) has officially discontinued support for many legacy versions, you can still find the installer through several channels: Key Features of Version 8
License for Quartus II 8.1 / Setup of Quartus II 7.2 - 292621
Unlike the paid subscription version, the Web Edition is free and includes:
Altera Quartus II 8.1 Web Edition for Windows is a legacy version of the FPGA design software, primarily used for developing and programming CPLDs and medium-density FPGAs. As a "Web Edition," it is available as a free download that does not require a paid license for its core features. Key Features of Version 8.1 Enhanced Performance & Timing