At DC Central Kitchen, a social enterprise in Washington, D.C., a fresh wave of volunteers arrives daily to help turn restaurant leftovers into meals for the hungry. “In three hours,” says founder Robert Egger, “I want volunteers to go from nervous amateurs to enthusiastic believers.” One clue that they’ve had a great experience: They post an online review of the nonprofit with the passion of someone who has just discovered a gem of a restaurant.

A better picture of the work that nonprofits do is coming into focus, thanks to increased collaboration by organizations that report on charities. User-generated content, written by those who have direct experience with nonprofits, now appears alongside more formal evaluations of charities on a variety of websites. For potential donors and volunteers, it adds up to “a 360 view of nonprofit effectiveness,” says Perla Ni, who founded GreatNonprofits in 2007 with this goal in mind.

Ni (founder and former publisher of the Stanford Social Innovation Review) launched GreatNonprofits in the wake of Hurricane Katrina. She recalls being frustrated by not knowing which organizations were doing a good job of responding to the disaster. As survivors’ stories emerged, she realized that some of the best response came from small organizations unknown outside New Orleans. Technology offered a solution to gather this scattered wisdom, leading Ni to create a Zagat-style charity review site.

It wasn’t long before GreatNonprofits—an upstart in the field—caught the attention of GuideStar, established in 1994 to create more transparency in the nonprofit sector. By partnering, the organizations have enabled user reviews to flow across both sites. Content sharing extends the reach of GreatNonprofits and adds another dimension to the information that GuideStar publishes about nearly 2 million tax-exempt organizations.

User reviews offer authentic insight “into the inner workings of a nonprofit and show real-time feedback that begins to paint the picture of effectiveness,” says Bob Ottenhoff, GuideStar president and CEO. His organization has invested time and resources in the partnership, he says, because “we believe that user reviews can ultimately be an important tool in measuring the impact and effectiveness of nonprofit organizations.”

User reviews are just one of several tools donors and nonprofits need, Ottenhoff cautions. GuideStar recently acquired Philanthropedia, which surveys social cause experts to identify nonprofits that are having the greatest impact in specific areas. Bringing together multiple perspectives fits GuideStar’s goal to “facilitate innovation and thought leadership in the marketplace,” Ottenhoff says. “We consider our partnership with GreatNonprofits as part of our test laboratory, for us and for the sector.”

The sector is responding. Two more organizations, Charity Navigator and GlobalGiving, have now joined the content syndication effort, which is managed on the back end by GreatNonprofits. Charity Navigator rates the financial health of more than 5,500 of the largest nonprofits using a star system. GlobalGiving is an online marketplace for nonprofits around the world.

User reviews posted on any of these sites now appear on all of them. “All our partners have their unique ways of reviewing charities and thinking of what their audience wants,” says Ni. By getting more organizations on board, she hopes to build a critical mass of reviewers. The number of reviews has increased threefold in the past year, with partner sites generating 35 percent of content. “Working together makes this information credible,” she says.

For nonprofits like DC Central Kitchen, there’s value in “empowering our volunteers,” says Egger, and inviting them to be critical. They can offer feedback that nonprofits need to hear. But, he adds, “it needs to go beyond ‘I (heart) this nonprofit.’”

As the charity evaluation field continues to evolve, Egger sees nonprofits searching for right-sized tools. “Everybody’s asking: What can the average nonprofit afford? What can the average volunteer (or donor) understand?” A platform that gives users a voice “has the potential to be a revolutionary tool in the sector,” Egger predicts.