Ever wanted to try a mobile app before you buy it but only had screenshots and a couple of reviews to look at before making a decision? Worse still, ever forked out cash for an app that doesn't do what you thought it would do? An Australian technology start-up is working to fix that problem, and has caught the eye and the backing of American investors.

In the same way that movies have trailers, App.io gives smartphone users the ability to try an app to get a taste of what it looks and feels like before buying it. Demos can be placed on blogs, websites, Facebook or Twitter and work on all platforms and do not require a plugin - all that is needed is a web browser.

Chris Nolet, Edward Dowling and Diesel Laws of tech start-up App.io. Credit:Kevin Warnock

So far the start-up has raised $US1.2 million ($1.27m) from investors and more than 8500 app developers have signed up to use the service.

Edward Dowling, 26, Diesel Laws, 29, and Chris Nolet, 28, founded App.io in April last year when Nolet and Dowling applied to get into Melbourne accelerator AngelCube with another idea. Their idea, originally launched as Kickfolio — an online portfolio product for app developers to showcase their work — was formed during their time at AngelCube and launched a month later.