Cash App Founder Bob Lee Remembered as 'Brilliant Investor' and 'Best Java Programmer in the World' The tech founder was known as "Crazy Bob" for his drive and passion.

Cash App founder Bob Lee, 43, died on Tuesday after an early morning fatal stabbing in San Francisco's Rincon Hill neighborhood. Lee had previously relocated to Miami and was in San Francisco for a visit.

Lee was born in Missouri and worked as an engineer before moving to San Francisco in 2004 to work for Google. After five years at the tech behemoth, where he worked on the Android core library, Lee was hired by Square to develop its app. He later became the company's first chief technology officer, a position he held until his departure in 2014.

In 2013, Lee developed the now widely used payment service, Cash App.

Lee's interests also transcended beyond business. In the wake of Covid-19, he helped the World Health Organization develop its app amid the global pandemic.

In November 2021, he joined MobileCoin, a peer-to-peer cryptocurrency platform, as the chief product officer.

Lee was affectionately known by many as "Crazy Bob" — a nickname he earned from his water polo days — because of his ambition and energy.

Friends, family, and tech contemporaries have been remembering their friend and colleague online.

"He was made for the world that is being born right now," MobileCoin CEO Josh Goldbard wrote on the company's website. "Bob was a child of dreams, and whatever he imagined, no matter how crazy, he made real. Bob was made for the new world."

Block Inc. co-founder Jim McKelvey told Bloomberg that he recruited Lee to work at Square.

"Jack [Dorsey], who is not prone to hyperbole, said Bob Lee was the best Java programmer in the world," McKelvey told the outlet.

Venture capitalist Wesley Chan extended his condolences in a LinkedIn post remembering Lee as a good friend, talented engineer, and "brilliant investor."

"Bob's energy was electric - his nickname was Crazy Bob (in a very good way) and every time he'd visit me when we were in SF together…I'd leave feeling energized and inspired," he wrote. "Bob, you'll be missed by so many. I learned a lot from you, and I'm not sure what to say other than what happened is just so crazy, in a terrible and tragic way."

Figma CEO Dylan Field remembered meeting Lee when he was a teen and "geeked out about programming."

So sad to hear of @crazybob's untimely passing. I first met him in summer 2006 — he didn't care that I was only 14 and we talked tech / geeked out about programming. We remained connected over the years and he was an early supporter of Figma. It's so hard to believe he is gone.

— Dylan Field (@zoink) April 5, 2023

Elon Musk Tweeted that he was "very sorry" to hear of Lee's passing.

On Facebook, Lee's father, Rick, wrote: "Bob would give you the shirt off his back." He noted that he moved with Lee to Mill Valley, California in 2019 and then to Miami in 2022.

"I'm so happy that we were able to become so close these last years," he wrote. Lee's brother, Tim, also shared his grief, writing on Facebook that Lee was "the best of us" and that he feels as though he's lost "part of [himself]."