The Good: Radical.FM offers completely free streaming music with zero ads. The Bad: The app is often unresponsive and has a confusing design. Searching for songs to add to your stations is a tedious process. The Bottom Line: Radical.FM fits the bill when you just want to jam out with some music, but its limited features won't please most music fans. Radical.FM (iOS|Android) is a music-streaming radio service with a twist. The app is completely free to use, and it doesn't have any ads. It's a direct competitor to Pandora, but takes a different approach.With Radical.FM, you create streaming stations based on genres of music, and the app pulls from its library of 25 million songs to fill out your station. That's different from Pandora, which asks you to name a song, album, artist, or genre, and then creates a station of songs with similar styles to the music you selected, using the Music Genome Project. I personally prefer Pandora's approach, because I feel that it better taps into what specific styles of music I want to hear, based on a combination of music composition and lyrical themes.Because the app is free, there are some limitations. You can't play any song on demand, but you can search for individual tracks and add them to your stations. New releases aren't always available. And, overall, the app doesn't feel polished. Still, if you can overlook the design flaws and minimal features, Radical.FM hits the spot when you just want to listen to music that's just a bit more personalized than regular radio.Pay (or don't) to playAs I mentioned earlier, Radical.FM's most unique feature is that the service is completely free to use, and it doesn't have any ads. Unlike Pandora's free tier, you won't see or hear any advertisements, and you can use the full app without paying a monthly subscription.The company gets by on donations from its listeners, which helps pay for the music licenses Radical.FM needs to play music. The more people donate, the better the app could feasibly become, with design updates and an improved experience. Yet, given that the app isn't that great to begin with, it's a tough sell to get people to fork over their money.You can donate as much (or little) as you want, either on a monthly basis, or make a one-time donation. Radical.FM does this because it says that everyone should be able to listen to music, whether they can afford a subscription or not.What's really great about this approach, is that, at least in my testing, the app doesn't bombard you with requests for donations. If you want to donate, you just swipe right to reveal the app's main menu and tap the banner that shows your name.Design and setupForget the sleek look of Spotify, the bright colors in Beats Music, or even the elegant design of Pandora; Radical.FM's aesthetic is plain and frankly a bit boring. With such a simple design, you'd think the app would be easy to use, but it's not as intuitive as it could be.There's a left-side menu that helps you navigate the app. You stations are at the top, followed by lists, and settings. You can swipe left and right through the app to open that menu, show the now-playing screen, and open up the search menu, which I'll touch on later. I urge you to swipe through the app, instead of tapping the tiny, hard-to-hit buttons that also reveal the same screens. Even then, you might need to swipe several times for the app to do what you want.To use Radical.FM, you need to sign up for an account using your email. You can also opt to sign up with Facebook, but that didn't work for me on the two Android phones I was using for testing. Radical.FM says that's a known issue its working to fix.You're the DJAfter you create an account, you can start building your first station, which is a simple process. You pick from a list of 21 genres, including Pop, Classic Rock, and Bluegrass. Each of those have at least two to three subgenres, so you can get more specific about your music preferences. You can include as many genres as you like in your station.Unfortunately, the genres feel limited and a bit outdated. Today, apps like Pandora and Spotify have creative, nuanced genres such as "Power Pop" and "Feel Good Indie Rock," so the more basic choices like Jazz, Hard Rock, and Motown feel a bit lackluster. What's more, because the genres aren't very specific, you might not always get the music you want in your stations.