Appster was an Australian mobile app development company, founded in 2011 by Josiah Humphrey and Mark McDonald.

[3] Appster was launched in June 2011 by 19-year-olds Mark McDonald and Josiah Humphrey, with $50,000 originally as a digital agency consulting to online e-commerce companies on conversion rate optimization.

The company opened an office in San Francisco with 5 full-time staff and estimated revenues in the Australian market of $10 million.

[10] February 2015, Appster partnered with Hobart's New Town High school in Tasmania to give students a hands-on experience coding and designing gaming apps.

[15] In 2019, it was reported that the liquidator was rallying creditors to pursue legal action against founders McDonald and Humphrey, alleging they traded while insolvent.