Quartus II
Quartus II is a software tool produced by Altera for analysis and synthesis of HDL designs.
Quartus II enables the developer to compile their designs, perform timing analysis, examine RTL diagrams and configure the target device with the programmer.
Quartus II Web Edition
The Web Edition is a free version of Quartus II that can be downloaded or delivered by mail for free. This edition provided compilation and programming for a limited number of Altera devices.
The low-cost Cyclone family of FPGAs is fully supported by this edition, meaning small developers have no overheads from the cost of development software.
License registration is required to use the Web Edition of Quartus II, which is free and can be renewed an unlimited number of times.
Quartus II Subscription Edition
Quartus II Subscription Edition is also available for free download, but a license must be paid for to use the full functionality in the software. The free Web Edition license can be used on this software, restricting the devices that can be used.