More than half of app developers (59 percent) are failing to generate sufficient revenue from their most successful app to cover development costs, according to research by app marketing company App Promo.

An even greater proportion (80 percent) said that the revenue they generate from their most popular app is not enough to support a standalone business.

The research found that the developers receiving the most revenue are also spending more time and money on marketing their apps. Developers earning US$50,000 or more from their most successful app made up 12 percent of those surveyed. People in this group spent an average of 14 percent of their time promoting their app with average marketing budgets of almost US$30,000.

However, 52 percent of respondents said they spend 5 percent or less of their time on promoting their apps and don’t have a marketing budget.

App Promo founder and CEO Gary Yentin said the research shows that developers need to do more than build apps if they are to earn significant revenue. “Developers have to spend money and time on marketing in order to succeed,” he said.