Yes, the downloadable installer includes a free 24-hour trial. The trial is exactly like the full application and has no feature limitations. In addition, you can buy and evaluate Radio Silence without any obligation for a full 30 days. If you aren't 100% happy with it, for any reason at all, you'll get your money back.
No. Firewalls like Radio Silence can't be sold through the App Store, because they have to peek inside the operating system to see the network connections of other processes. The App Store doesn't accept applications that need this privilege.
Once your trial is over, Radio Silence will ask for your license key. When you buy Radio Silence, you get your license key to your email inbox. If you want to register your license key before the trial is over, choose "Register…" from the application's menu.
No. The trial version is the real thing. It simply has a time limitation. Once you input your license key, the time limitation disappears.
The emails are usually sent within one minute of purchase. If you don't see the email in your inbox, check your spam folder.
No need. You can install Radio Silence on all the computers you have. The license is for your personal use, and is not tied to a single computer.
Radio Silence runs on all versions of Snow Leopard (10.6), Lion (10.7), and Mountain Lion (10.8).
No, the Radio Silence firewall is invisible and runs automatically when you start your Mac. If you are happy with your list of blocked applications, you don't have to do anything.
Yes. There's no need to keep the application window open. The user interface is only used to make changes to the actual firewall. Even if you close the application window, the firewall stays active and vigilant.
It lets you make a list of applications that aren't allowed to access the internet. You can add as many applications you want to the list through a simple user interface.
The built-in firewall doesn't stop outbound traffic at all. You can only block incoming connections with it, which doesn't help with applications that want to phone home. The Radio Silence firewall does stop outbound connections.
Yes. Radio Silence works with any applications you have installed. (This particular question is asked so often that it is answered here separately. Please be nice and don't pirate software.)
You can simply move the Radio Silence application to the Trash. If you want to be thorough and remove all traces of the app, also delete the following two files and one directory: