Somewhere over the country, Edward Kim watched his mother run her business's payroll on a plane. She was using software he had helped build. He has called it a mind-blown moment.
To understand why it hit him, go back to Los Angeles. His mother, Sheena, a South Korean immigrant, ran the front desk of his father's small medical practice. When the family started selling an improved diabetic lancet online, Edward, still a boy, wrote a program with a tool called Endicia that weighed the packages and printed the postage. 'He made me a software with Endicia,' she later told Fortune.
They say a lot about what they had watched: parents with no spare hours for paperwork.
Hold on to that picture, because his partners lived the same one. Tomer London grew up in Israel and worked in his father's clothing store, where he wrote inventory software and then carried it door to door to shops in Haifa. His mother, Irit, says he sold plenty of software before Gusto. Josh Reeves grew up in Marin County as an Eagle Scout; his mother, Eliana, came from Bolivia, and her favorite story is of him hauling wooden steps up a Muir Woods hill with park rangers. The steps are still there.
So the three men who started ZenPayroll in 2011 were each the child of a small business. They came through Y Combinator's Winter 2012 batch and launched on December 11, 2012, with a $6.1 million seed that included Box's Aaron Levie and David Sacks. The sources say little about what any of them feared. They say a lot about what they had watched: parents with no spare hours for paperwork.
What almost nobody notices is how the three families ended up. In 2014 the mothers met for the first time in Haifa, at Tomer's wedding, and spent three days together on a bus tour of Israel. They have since traveled together to Tenerife and Disneyland.
The company grew the way those households would have wanted: simply. By August 2013 it said it moved more than $100 million a year. In September 2015 it dropped the Zen name for Gusto and added health benefits, and that December it hit a $1 billion valuation. A June 2025 employee tender valued it at about $9.3 billion, below the $10 billion-plus figure quoted from 2021. In 2026 Gusto passed $1 billion in trailing revenue, which Reeves stressed was cash collected, and it has been cash-flow positive for years.
The cost is harder to find in the record than the reward; no one has said what the early years took from the founders. What is documented is the thing they built from.
A founder can take one idea from this: the customer was never an abstraction to these three. They had sat at that dinner table, and they built the product their mothers would approve of.