WiFiSpoof 4+

It does what it advertises, which is spoof your MAC address.

However, some features are simply broken. For instance it will always list your old MAC address under "Current Address", whereas previous versions properly displayed the spoofed address. So without external verification, there’s no real way to be sure the app is working.

It would also be nice if it had added features, considering everything it currently does could be accomplished with some Googling of the proper terminal commands. (A nice feature would be the abilitity to automatically clear cookies or cache, for instance, as some of these public wifi networks that try and time you out of free access, also like to use tracking cookies rather than simply MAC addresses, but just an idea.)

Loved the trial version, went to buy it here on the App Store for my Mac Book Air running High Sierra.
Had quite a few problems with installation (but eventually succeeded). The developer needs to post HERE on the App Store that you need to throw away the Trial Version to install the Paid version.
They sent me that in an email after I wrote to their support dept when I was having endless install problems.
Anyway, now that the installation problems are solved (took two hours) I do have to say that this little piece of software is like magic.
If you have reasons why you would need to change your MAC Address, this thing is superb for that purpose.
Tested again and again in a situation where changing the MAC Address was critical - worked every time, and flawlessly.
One side note - again the Trial version does not work exactly like the Paid version - very similar but some steps are made easier in the Paid version.
On one hand this is a good thing, but on the other hand it is a bit confusing for the first few moments of the Paid version as you are trying to use buttons you had to use in the Trial but not in the Paid. Also there is an absolutely critical “read me” file in the Paid version that you must not ignore.
If you have a need to change your MAC Address then I can highly recommend this software.
2014 Mac Book Air, High Sierra

The program is user friendly and very nice to look at, while working exactly as intended to. On my network, it takes a couple minutes to connect when I'm switching to a MAC address that isn't my computer, but when it does connect, it works flawlessly. Keep in mind that there are multiple free programs on the web you can use if you're a normal person who doesn't want to spend $20 to do something you can do on the command line. I wasn't very happy with the price, but otherwise, a very solid program.