He spent five years connecting the fitness world. Then he left to fix the one part still broken - the sign-up.
Every runner knows the moment. You found the race. You're excited. And then the registration page loads - a relic of an earlier internet, asking for your emergency contact in triplicate. Zack Isaacs decided that moment was worth a company. "If you've ever signed up for an event, you know that it's a broken experience," he says. "We want to change that." Movemint, the company he co-founded in 2023, is his answer: a mobile-first platform that treats the sign-up not as a chore but as the first stride of the event itself.
Every event is so much bigger than race day. It's a million details that need to go right.- ZACK ISAACS, CO-FOUNDER & CEO, MOVEMINT
Most founders building software for athletes have never pinned on a bib. Isaacs has. He brings more than a decade in the endurance world to Movemint, and he ships features by living inside the problem - he registers, he runs, he reads the results page on his own product. That feedback loop is the whole point. When the Oakland Track Club and the Marin Mile each doubled their participant numbers after switching to Movemint, it confirmed the founding hunch: the sign-up itself was the bottleneck, not the sport.
Today Movemint is a three-sided machine. Participants discover and register for events. Organizers - race directors, timers, clubs - get a free platform with daily payouts, customizable branding, donation tracking, and a checkout tuned to within an inch of its life. And brands get a place to sponsor and measure. Isaacs is wiring all three together, and doing it fast. The company has roughly tripled its business every quarter since launch.
In October 2017, Strava hired Zack Isaacs to do something the company had not yet done at scale: open itself up to the rest of the fitness world. He was the first API hire, which is a polite way of saying he became the connective tissue of connected fitness. Over the next five years he built the partnerships that let a Garmin watch, a Wahoo computer, a Peloton bike, and a Zwift ride all land in the same feed. If you have ever finished a workout on one device and watched it appear in Strava seconds later, you have used something Isaacs helped wire together.
He didn't stop at plumbing. Isaacs led engineering for the 0-to-1 launch of paid Routes, which became one of Strava's most lucrative features. He learned, in other words, both halves of the job he holds now - how to connect an ecosystem, and how to turn a feature into a business. When he left in December 2022, he took both lessons with him.
The partnerships Isaacs brokered put Strava at the center of connected fitness - a position he would later rebuild for live events at Movemint.
No endurance athlete does great things all by themselves. Look for people who want to be on a team, who want to bring each other up.- ON HOW HE BUILDS, FROM ATHLETE TO FOUNDER
Isaacs runs the company the way he runs a season - small experiments, honest feedback, and a team that carries each other through the hard miles. Curiosity over certainty. Customers over committees.
He hires for people who want to support each other - the same instinct that gets an endurance athlete across a finish line they couldn't reach alone.
Race directors describe Movemint as customer-focused and fast-moving "in ways that some other platforms can't be." Speed is a feature.
He validates ideas with small experiments and honest data, then doubles down on what works - a habit carried straight from the API days.
There is a particular kind of validation in having the world you left invest in the thing you built next. Movemint's pre-seed, which closed in May 2024, was led by Underscore VC with participation from Fitt Capital, Green D Ventures, and angels including Kiwi Fitness co-founder Olia Birulia. Then came the signal that mattered most to anyone who knows the space: Strava co-founder Michael Horvath joined the board.
"The support we've received from the athletic community has been incredible," Isaacs says. "We have the best team, and we're going to continue building as fast as we can for our community." The events lining up behind him read like a tour of the sport - the Golden Trail World Series Headlands 27k, the Tracksmith Twilight 5000, the Rock Cobbler, TransRockies, and the Boston Road Runners AAPI 5k series.
If you've ever signed up for an event, you know that it's a broken experience. We want to change that.- THE THESIS, IN ONE SENTENCE