Photo calorie app Cal AI, downloaded over a million times, was built by two teenagers

In a world filled with “vibe coding,” Zach Yadegari, teen founder of Cal AI, stands in ironic, old-fashioned contrast. 

Ironic because Yadegari and his co-founder, Henry Langmack, are both just 18 years old and recently graduated from high school. Yet their story, so far, is a classic.

Launched in May, Cal AI has generated over 5 million downloads in eight months, Yadegari says. Better still, he tells TechCrunch that the customer retention rate is over 30% and that the app generated over $2 million in revenue last month. 

Although TechCrunch couldn’t validate his download and revenue claims, Cal AI does have a 4.8-star rating on the Apple App Store, with 66,000 reviews, and over 1 million downloads on Google Play with a 4.8-star rating on nearly 75,000 reviews.

The concept is simple: Take a picture of the food you are about to consume, and let the app log calories and macros for you. 

It’s not a unique idea. For instance, the big dog in calorie counting, MyFitnessPal, has its Meal Scan feature. Then there are apps like SnapCalorie, which was released in 2023 and created by the founder of Google Lens.

Cal AI’s advantage, perhaps, is that it was built wholly in the age of large image models. It uses models from Anthropic and OpenAI and RAG to improve accuracy and is trained on open source food calorie and image databases from sites like GitHub.

“We have found that different models are better with different foods,” Yadegari tells TechCrunch.

Along the way, the founders coded through technical problems like recognizing ingredients from food packages or in jumbled bowls. 

The result is an app that the creators say is 90% accurate, which appears to be good enough for many dieters.

Teen coders and a hacker house

Yadegari is also earning some fame for his early success. But, unlike teen coders growing up with AI copilots, he was mastering Python and C# in middle school, he said.

Yadegari built his first business in the ninth grade and sold it for $100,000 to another game company, FreezeNova, when he was 16, he tells TechCrunch. “After quarantine, schools gave out Chromebooks to all of their students, and unsurprisingly, kids tried to abuse this by playing games in school,” he said.

The school responded by blocking web access to those game sites. So he “saw an opportunity” to build a website that gave access to all unblocked games.

The best part? He called the website “Totally Science” so the school wouldn’t block it, too. 

With that sale, he and Langmack watched Y Combinator videos and socialized with the coder crowd on X looking for a new idea. He met Blake Anderson on X, who also became a Cal AI co-founder. Anderson, now 24, had earned notice as a young consumer app coder, too, for creating ChatGPT dating advice apps like RizzGPT and Umax. 

Yadegari and Langmack had their idea after Yadegari began hitting the gym to gain weight and “impress girls,” he said, smiling.

Then they made another cliché choice: They moved to San Francisco to live in a hacker house while building their prototype.

But while there, Yadegari, the son of two lawyers, learned a contrarian lesson. He discovered he wanted to go to college and not become a classic Silicon Valley dropout type.

“Twenty-four-seven grinding, sleeping on the floor, actually, one of the nights, and it was a very fun time, and it taught me a lot,” he said of the experience.

But he looked around. “We were surrounded by people that were in their late 20s or 30s all day. And I realized that if I didn’t go to college, this is what life would be like.”

While he hasn’t yet determined which university he’ll attend, he and Langmack are still having fun running their company. It now includes another co-founder, Jake Castillo, 28 who is COO and running influencer marketing, as well as eight full-time employees between developers, a designer, and social media managers.