Adam Reid Levitt, 36, formerly of Bryn Mawr, a computer engineer, software entrepreneur, and best friend to many, died Friday, Dec. 22, at a Los Angeles hospital of complications from a 2017 bone marrow transplant intended to treat an immune disorder.

Mr. Levitt had moved to the West Coast four years ago to work with Kenny Berlin, a friend from his Radnor Township school days. The two partnered in 12Twenty Inc., a software firm that markets an employment database to colleges and universities around the world. The database links potential employers with college students and alumni in search of career jobs.

The company's name was derived from 12:20 p.m., the time they talked by phone each day when not in the same office.

"Adam was an engineer who could talk to human beings," Berlin said. "Adam did all the coding, and I did everything else. We have grown a very large company, and today Adam's legacy is that we've built something much more than the two of us."

Smart, driven, and always on the move, Mr. Levitt was part of a group of Radnor High school chums who dreamed of doing something involving information technology. Their dream came to fruition with the creation of 12Twenty in 2010.

"He had the tech drive, and Kenny had drive and business acumen. You couldn't put together a better team," said longtime friend Danny Uhr, who watched from the sidelines.

Born in Philadelphia, Mr. Levitt grew up in the Radnor Township side of Bryn Mawr. He graduated from Radnor High School in 1999 and received a bachelor of science degree in information technology from Syracuse University in 2003. He earned a master's degree from Pennsylvania State University in 2005. While at Syracuse, he pledged Psi Upsilon fraternity.

Mr. Levitt had a lifelong passion for computers and coding, or writing software, his family said.  As a teenager, he was irrepressible – he always wanted to be doing something, said Uhr.

"He never liked to sit still. He made the most of every minute of the day," Uhr said.

In his teens,  Mr. Levitt was one of the youngest chat-room monitors for America Online.  He was a natural problem-solver and loved the challenges that coding provided, his family said.

His first job out of college was working on projects at Lockheed Martin in King of Prussia. His second job was in New York City with the Trade Card Co. In 2010, when Mr. Levitt and Berlin cofounded 12Twenty, the cloud-based software programs Mr. Levitt developed were the first systems of their kind to integrate job tracking and on-campus recruitment on one platform, Berlin said.

Although Mr. Levitt was diagnosed with an immune disorder in his early 20s, he never let it interfere with his work or ruin his zest for life, his friends said. He enjoyed living in Santa Monica, with Sandy Zeger, whom he married in 2015.

"Adam lived his life with a 'joie de vivre' that was infectious to all those around him," his wife said. "I want to forever remember his spirit, and live my life thinking, 'What would Adam do?' "

Among his favorite pastimes were traveling, cooking, tennis, and hiking. But beyond those, Mr. Levitt spent a lot of time being a best friend to scores of people – so many in fact that when he was married, he had a wedding party of 10 groomsmen. He had been best man or honorary best man at each of their weddings. All considered him their best friend, Uhr said.

"That was his legacy," said Uhr. "He was able to give enough time to so many people, he was their go-to. It was not a one-sided relationship. That was where he was at his best."

Friend Scott Rubens, who knew Mr. Levitt from age 3, said: "His magic was the ability to have more close friends than anybody I know, and the ability to connect people. When he had free moments, he went down his list of calls. He just cared immensely.

"I'll miss him forever," Rubens said. "He's leaving behind a lot of good people who will never forget what he's taught us. I love him."

His 12Twenty cofounder called Mr. Levitt "the better half" of the company.  "Adam was a kind, thoughtful, and generous leader, and many considered him to be one of the finest people they had ever known," Berlin said. In addition, Mr. Levitt helped others in the company be successful.

In addition to his wife, he is survived by his parents, Linda J. and Robert E. Levitt, and a sister, Ashley B. Levitt.

Memorial services were held in December. Burial was private.