"Nonprofits want to engage their audience on Facebook but have had consistent issues with doing that with some of the ways that the algorithms have worked in terms of displaying information on people's News Feed," said Rick Cohen, director of communications and operations for the National Council of Nonprofits.

From mailing in checks to texting, the way donors contribute is still a mixed bag because some people are still wary about putting their credit card information online, Cohen said. In 2014, online donations represented fewer than 10 percent of all charitable giving, but that continues to grow, according to Network for Good's Digital Giving Index. But the study also showed that social fundraising has been booming over the past few years, with donation volume growing 70 percent last year.