College development offices have for decades adapted the consumer-profiling techniques used by marketers at for-profit companies. Some schools employ their own in-house researchers to follow, say, the stock market transactions of individual donors or to look up the value of their homes on Zillow. Others buy information from data brokers on their most generous alumni or prospective donors.

Blackbaud, a 30-year-old company in Charleston, S.C., markets donor management software and services for nonprofits. It helps colleges and universities identify, rank and target their best fund-raising prospects by combining a school’s historical giving records with data from outside sources, including an individual’s “overall wealth, income levels and hidden assets,” according to the company’s website. Blackbaud also maintains a database of more than 50 million donations; the company uses it to analyze donors’ gifts to other institutions to help schools understand the giving capacity of certain alumni.

But EverTrue is among a handful of start-ups using social media to try to predict the willingness of graduates to donate or volunteer for other activities, like interviewing college applicants. Schools have historically relied on donor databases and have also used alumni attendance at reunions as proxies for willingness to donate. The start-ups are meant to complement those strategies with data visualization tools that allow fund-raisers to map their graduates’ locations or graph their social media interactions with a school.

At a moment when President Obama is pushing for federal consumer privacy legislation, these nascent donor data-mining techniques demonstrate how easy it is for companies to repurpose the details that individuals volunteer about themselves in one context for a different use.

“I do think there’s an ethical issue. It’s one thing to estimate someone’s wealth, but then to gauge how willing they are to give, you have to look deeply into a person’s life,” says Pam Dixon, executive director of the World Privacy Forum, a consumer group in San Diego. “I’m not sure alumni would appreciate or want that — if they knew about it.”