Vintage baseball encyclopedias displayed at the Sports Reference headquarters, located at Summit Presbyterian Church in Philadelphia on Jan. 16. (Mark Makela/The New York Times)

PHILADELPHIA — While writing a sermon in September, Cheryl Pyrch, the pastor of Summit Presbyterian Church, needed an assist. On the topic of greatness and Jesus Christ, she wanted to open with recollections of greats in other spheres.

She did not have to look far for a source.

Having encountered Wilt Chamberlain in passing almost 40 years ago, she decided he was the great she wanted to highlight. And details of his career — four Most Valuable Player Awards, seven NBA scoring titles — were close at hand, literally and figuratively through Sports Reference, a monolith of sports data websites that just happens to rent space from the church.

“I didn’t know all this in 1980,” Pyrch told the congregation as she described Chamberlain’s awards during the Sunday service. “I got it yesterday from a Sports Reference website.”

The ubiquitous Sports Reference family of websites — Baseball-Reference.com, Basketball-Reference.com, Pro-Football-Reference.com, Hockey-Reference.com, and so on — are some of the most popular sports almanacs on the internet.

They draw users of all kinds, from people casually searching for a trivia answer to owners of professional teams. Aided by an overhaul of its mobile website, Sports Reference’s founder and president, Sean Forman, said the group of sites drew 1 billion page views last year, a record for the company.

Sports Reference, however, does not have the gleaming offices or huge staff of a digital titan. It has 11 full-time employees and is headquartered on the third floor of a building at Summit Presbyterian in Philadelphia, behind the 100-year-old main church and above the gymnasium, which is often used as a day care center.

“Walking through it to come in and out, sometimes you’re going through 3-year-olds tossing balls,” said Mike Kania, 38, who eight years ago became one of the company’s first employees. “I worked for AOL for a long time where we had a badge to scan at the front door, people there and a front desk. It’s a lot different from that.”

It is, in fact, a point of pride among Sports Reference employees that the sites have grown from humble beginnings into oft-used resources. Until late last year, Forman, 47, was cleaning the office and taking out the trash. (He has since hired the church’s janitor to take over those duties.)

They are among the most popular sports-related sites. Basketball-Reference trails only NBA.com, while Pro-Football-Reference is second to NFL.com, according to SimilarWeb. Nearly two decades after Forman created Baseball-Reference, it ranks third among baseball sites, behind MLB.com and MLBTradeRumors.com. (Baseball-Reference, however, is the top draw in Forman’s stable.)

The sites are not just for casual fans. J.J. Redick, the Philadelphia 76ers guard, pays for an advertising-free Basketball-Reference subscription. John Henry, the principal owner of the Boston Red Sox and Liverpool F.C., uses Baseball-Reference’s Play Index to manage statistical searches. Scott Boras, the well-known baseball agent, donated $100 to the company during its infancy because he had relied on the site’s data while negotiating a contract for slugger Andruw Jones, Forman said.

“I use it daily,” said Thad Levine, the Minnesota Twins general manager, although his team, like many others, generates its own advanced and proprietary data.

“We went so far as to hire one of their back-end programmers,” added Levine, referring to Hans Van Slooten, who oversaw Baseball-Reference until June, when the Twins hired him for their front office.

The sites are still expanding and developing. Forman said he envisioned Basketball-Reference eventually surpassing Baseball-Reference in traffic as a result of the data revolution in the NBA. And over the summer, Sports Reference began another substantial undertaking: a soccer website, FBref.com, which the company hopes will be as comprehensive as its other sites. In a twist from its current offerings, the company is planning to make the soccer site bilingual, with English and Spanish versions.

The sites are painstakingly tweaked for updates and corrections. Some errors are reported through the dozens of emails the company receives daily. One came from the mother of Casey Fossum, a former major league pitcher. She wrote to say that her son’s date of birth was wrong. It was corrected.

Sports Reference started with Baseball-Reference in 2000, when Forman, looking to avoid work on his doctoral dissertation on applied mathematical and computational sciences at the University of Iowa, began building a website from the CD-ROM that accompanied the printed Total Baseball encyclopedias. He hoped to make historical data more accessible.

Forman, who has contributed to The New York Times’ baseball coverage in the past, expanded his endeavor by creating Sports Reference in 2004. Three years later, he formalized loose affiliations with Pro-Football-Reference (founded by Doug Drinen in 2000) and Basketball-Reference (founded by Justin Kubatko in 2004). Kubatko left Sports Reference in 2013 because of what he called “creative differences.”

In 2007, Forman still fit the stats nerd stereotype, working out of the basement of his home and staying up until 1 a.m. updating or improving the website. The year before, he had left his full-time job of six years — professor of mathematics and computer science at St. Joseph’s University in Philadelphia — because it was too hard to juggle both. He also needed a better place to work.

So Forman turned to his church, which had space to rent.

Sports Reference’s seven websites are usually updated automatically, mostly from official feeds of statistics that the company pays for. Some data, such as roster transactions or salary information, is input manually, and there are always bugs to fix.

That the little company in her church has become so important, with leading sports websites, earned a laugh from Pyrch. She had been to the sites once or twice, including the time she did sermon research.

“I think that both myself and most of the congregation would not realize what kind of a powerhouse Sports Reference is,” she said. “I don’t really know a lot about numbers or computers, but 1 billion is a lot.”