Altera/Intel provides "free" tools (Quartus Prime Lite) in very much the same way as Xilinx (ISE/Vivado). They're "free" in the sense no money is exchanged. But you do need to register; you need to be logged into their website in order to download the installer; and, when run, these tools do communicate details back to the "mother ship". For Xilinx this "feature" is called WebTalk, for Altera/Intel this "feature" is called TalkBack. Unlike Xilinx, Altera/Intel doesn't seem to provide a FAQ or website with information or details about TalkBack (or, at least, my google-foo wasn't strong enough to find it).
The download for Quartus Prime Lite is just a simple tar (it is not compressed). The download for version 126.96.36.1992 (the latest as of this writing) is 6.1GB. At first it seems odd that the tar is not compressed, but when I compress it with xz, the resulting file is 8.1GB! In any case, this large download causes me the same issues I had with Xilinx's ISE. Since a registration is required, and I have to be logged in to download the installer, and the webpage likes to automatically log me out after a period of inactivity, and my internet download speed is slow, I ended up having to make several attempts to download the complete 6.1GB file.
On the plus side, however, installing Quartus Prime Lite doesn't involve
any license shenanigans. If you download the correct flavour (i.e. the
"lite" version) there's no need to mess around with obtaining,
installing, and managing a license file. Presumably, this would make it
easier to install the software on a different machine and continue
development. In contrast, the required license file for ISE/Vivado is
locked to an ethernet MAC, so if you move the software or the MAC goes
away, you'd be locked out of your Xilinx tools until you rectify the
Another plus for the Quartus Prime Lite software is that this one tool handles all the Altera products. There's no need for one tool to do one set of products, and another tool for newer products.
One of the ironic things about the install is that at one point it asks me if I want to enable the TalkBack "feature". Of course I don't want to enable TalkBack, but the install likes to tease me into thinking that I might be able to install the product without this feature. I can, of course, not install/enable TalkBack, but then I'd need a paid license/subscription. To use the "free" tool, TalkBack must be enabled. By default this "Do you want to enable TalkBack?" button is not checked, forcing me to explicitly turn it on (because I so very much want to enable this "feature"!!).
Other than the above, the install is pretty straight-forward. No libraries need to be deleted (as is required with the Xilinx ISE install), no other "gotchas". Just give it a place to install itself, tell it which products you intend to use, enable TalkBack (yay!), and it does the rest.