You can’t look up Philly property owners by name anymore. City cites ‘security matters.’

Philadelphia officials have reprogrammed the city’s property-search website to remove the ability to look up properties by the names of their owners, citing undisclosed security concerns.

Under the change implemented about a week ago, users of the search at property.phila.gov can still find out who owns a property by inputting an address. But users can no longer conduct a search by entering the names of people or companies to see the addresses of properties they own.

“We decided that disabling the search function can help prevent any heat-of-the-moment incidents that would target a property owner, while still keeping this public information public,” deputy finance director Catherine Lamb, whose agency maintains the data, said Monday.

The change comes as activists increasingly embrace a tactic of tracking down the addresses of public officials to hold protests outside their homes.

Demonstrations have been held in recent months outside the homes of Mayor Kenney and former managing director Brian Abernathy, but it was unknown whether organizers found the officials' addresses through the property-search site.

“The overall temperament of events right now” has prompted officials to reconsider issues of “access to information and public safety and people’s safety," Lamb said.

City spokesperson Mike Dunn declined to identify people who have voiced concerns about the search-by-owner capability because they had not given their permission. He also would not discuss the timing of the change “because it involves security matters.”

The change pulls Philadelphia out of step with neighboring Bucks, Chester and Montgomery Counties, which permit owner searches on their websites, although Delaware County and Pittsburgh don’t offer those capabilities, according to a survey completed by the city to help inform its decision to pull the function.

Other big cities including New York, Los Angeles and San Francisco also don’t allow such searches, while Dallas, Miami and Boston do.

About 10,000 people had been performing such queries each month on Philadelphia’s property-search website, which debuted five years ago, to look up properties by the names of their owners, according to city data. That’s about 10% of all those using the site.

People wishing to search for properties by owners' names can still do so by downloading raw data sets from city websites and opening them as spreadsheets on their computers, Lamb said.

George Donnelly, a lawyer with the Public Interest Law Center, said that’s easy for people who know how to sift through big data sets on spreadsheets and have computers that are up to the task.

But he said the simple search that used to be available on the city’s website was empowering for people without technical backgrounds and speedy computers and who had few ways of getting more information about current or potential landlords.

For example, he coached clients looking for new rental homes to see what other properties were owned by prospective landlords in order to check those addresses against other city websites that list health and safety violations.

“Not being able to search by owner, it does allow some landlords to operate a little more in the shadows than they did two weeks ago,” he said.