It just got easier to apply to multiple charter schools in Philadelphia.

Starting Friday, a new website, Apply Philly Charter, enables parents and students to apply to more than 70 of the city's charter-school campuses — as many as they want, with one online application.

Its backers say it's not intended to boost enrollment at charter schools, which are publicly funded but aren't run by the School District. About 70,000, or one-third, of Philadelphia public-school students attend charters.

"The purpose of Apply Philly Charter is not to expand the charter sector," said Mark Gleason, executive director of Philadelphia School Partnership, a nonprofit that funds charter, district, and private schools in the city and is operating the site. "It's to make sure every family has easy and equitable access to the charter sector, if they want it."

As school options have grown, cities have moved to streamline applications. "It's a pretty commonsense step in a city with a lot of choice," said Robin Lake, director of the Center on Reinventing Public Education at the University of Washington Bothell.

Some, including Denver and Washington, D.C., have gone beyond Philadelphia's initiative, creating a unified enrollment system for district-run and charter schools. But the concept has sparked controversy.

NEA Today, the national teachers' union publication, has labeled common enrollment "the newest page in school privatizers' handbook." In Boston, a proposal for a unified enrollment system drew "vehement opposition" from some parents, including opponents of charter expansion, according to the Boston Globe.

In Camden, which unified enrollment for its district and charter schools in 2015, the president of the local teachers' union has urged parents to boycott the system, which is funded in part by the Laura and John Arnold Foundation. It has supported certain charter-network expansions and awarded up to $1.4 million to support Philadelphia's new charter application process.

Unified application systems are "a great tool for ensuring equitable access to great public schools," Neerav Kingsland, managing partner at the City Fund, a nonprofit funded by the foundation, said earlier this year.

Five years ago, at the request of an alliance of district, charter, and archdiocesan schools, Philadelphia School Partnership put forward a plan for a unified system. But "we decided to pull the plug, for a number of reasons," including that it was Superintendent William R. Hite Jr.'s first year and the district was still facing a budget crisis, Gleason said.

Critics questioned who would run the system and how students would be assigned, and some opposition came from families whose children were applying to the district's special-admission schools.

This time, Gleason said, "we decided to proceed more cautiously" in simplifying the enrollment process.

Since 2014-15, the Philadelphia School District has also conducted its application process online and has since received more applications for special-admission and non-neighborhood schools, spokesperson Lee Whack said. "We want to certainly keep that going. Whether students and families are selecting district or charter schools, we encourage participation," Whack said.

Apply Philly Charter doesn't govern enrollment. Participating schools will still run their own lotteries. But they must conduct them between Jan. 28, the application deadline, and Feb. 19, the deadline for charters to let students know whether they have been accepted.

Not all charter schools are participating. "For certain charter schools that need applicants, I think that it works," said Ed Poznek, CEO of Christopher Columbus Charter School in South Philadelphia. But, he added, "we have such an extensive waiting list, we could open another school and never need another application."

Scott Gordon, CEO of Mastery Charter Schools, said the network's 18 Philadelphia campuses are participating because it would benefit parents. "We feel like we're part of a system, and parents should have access in as easy a way as possible to that system," Gordon said.

The Apply Philly Charter website — which will be available to use at the High School Fair Friday and Saturday — requires parents to create an account with an email address. It then allows them to create a family profile with information about their children, including their current schools and grade levels, and to select from a list of charter schools.

The process will yield new data, including how many schools the average family applied to and neighborhoods with high concentrations of applicants. It "should have some value for policymakers," Gleason said.