Download the ISO file. Do not burn it to a physical CD unless you have a retro PC. Right-click the ISO in Windows 10/11 and select Mount.
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.
FEATURE web quartusd 8.1 permanent uncounted 0123456789AB HOSTID=ANY \
ISSUER="Altera Corporation" ISSUED=1-jan-2008 NOTICE="Web Edition" \
SN=WEB-EDITION-81
If you don’t have legacy hardware constraints, consider these modern free options: Altera Quartus II 8.1 Web Edition -Windows- free download
| Software | Supported Devices | OS | |----------|------------------|----| | Intel Quartus Prime Lite (v18.1+ for legacy, v20.1+ for current) | Cyclone IV, V, 10 LP, MAX 10, etc. | Win 10/11, Linux | | Lattice Diamond (free license) | Lattice FPGAs (MachXO2, ECP5) | Win/Linux | | Yosys + nextpnr (open source) | Lattice iCE40, ECP5; basic Altera MAX | Linux/WSL | | Vivado HL WebPACK | Xilinx 7 series, Zynq, UltraScale | Win/Linux |
For very old Altera MAX 7000/3000A, Quartus II 8.1 may be the last version with support. Download the ISO file
Do you really need version 8.1?
Summary: Quartus II 8.1 is free (Web Edition) and functional, but obtaining the installation files requires third-party archival sources. Installation on modern Windows is possible but requires Compatibility Mode settings and manual driver management. If your hardware supports it, upgrading to Quartus 13.0sp1 is highly recommended for better Windows compatibility. FEATURE web quartusd 8
Disclaimer: Altera (now Intel) has moved these legacy files to an archive. Because this software is classified as "Legacy," it is typically offered "as-is."
Do not download "Quartus II 8.1" from random torrent sites or unverified third-party uploaders. These files are often infected with malware. Instead, use the official Intel legacy archive.
How to get the official free download: