There are plenty of online music services out there, and while we’re anticipating another to launch this week, Rdio is making its services available for free, provided you’re only listening for six months…ish.

Competition is heating up in the world of online streaming platforms, and with the smorgasbord of streaming solutions out there, we’re definitely not starved for choice.

Rdio seems to realise this, and is making its online library of 18 million songs available for streaming over your web browser or the Rdio desktop app free for a period of up to six months, up from the one week trial the company normally offers.

The terms aren’t quite as simple as “listen to free music,” with Rdio saying that you can listen for up to six months “depending on how many songs you stream,” which tells us that you’ll probably get a set amount of songs you can listen to per month before you have to upgrade, though the service will tell you how much free music you have on your profile page.

Once you’ve eaten up your free songs, so to speak, Rdio will ask you to plonk down money, with $8.90 per month netting you the access to the web and desktop apps, while $12.90 per month grabs you streaming over the mobile phone and iPad, with offline caching included in this plan and access through wireless devices from Sonos.

The sort-of-freebie is live now, and should offer some interesting competition for Spotify which, like Rdio, offers up an iTunes-like library of songs and albums in its service.