Many web-based businesses rely on a 'freemium' model: a small pool of users paying for premium services while the majority use the basic option for free. That works well in some cases, but if access to the service depends on letting other developers access your core APIs, how do you define the limits on what they get for free?

Aussie-developed service Rome2rio has long been a Lifehacker favourite for its ability to show the full range of travel options between any two locations: flying, trains, buses, boats and more. Now you can access the same features via an iOS App.

We've loved locally-developed multi-modal travel search site rome2rio ever since it launched, and its latest feature addition makes it even more useful. You can now plan and share multi-hop trips, very useful if you're planning a big overseas holidays and want to debate the merits of the train versus the ferry versus a cheap airline you've never heard of with your travel companions.