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Napkin Math

YC X26

San Francisco, US · Founded 2026 · 3 employees · 1 known investors

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An AI-powered food journal application that personalizes nutrition guidance based on individual health goals and lifestyle constraints rather than generic calorie-tracking recommendations.

Also known as Paper Star

ConsumerUnited States of AmericaAmerica / Canada

Founders & leadership· Y Combinator alumni (X26)

Napkin Math was founded in 2026 by Jynnie Tang, Manuel Castro, and Claire Nord.

JTJynnie Tang
Jynnie TangCo-FounderJynnie Tang previously worked at Retool and One More Multiverse, and studied at MIT. She is now building Napkin Math, an AI-powered food journal application.
MCManuel Castro
Manuel CastroCo-FounderManuel Castro previously worked at Sonos, a healthcare technology company, and Verkada before founding Napkin Math, an AI-powered food journal application.
CNClaire Nord
Claire NordCo-FounderClaire Nord previously worked on OS security at Apple and as an engineer at Samsara, and holds a degree in Computer Science from MIT (2019). She is currently building Napkin Math, an AI-powered food journal application.

Investors · 1

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Related companies · 1

EveryEvery is a media and subscription publication offering essays and columns—such as Katie Parrott's "Working Overtime"—about how AI is changing work and careers. It provides daily insights and early access to AI tools for a subscriber audience of leaders, builders, and innovators.

Companies working in the same space as Napkin Math.

In the news

Napkin Math - hyper-personalized AI food journalycombinator.com · May 2026

Frequently asked questions

What does Napkin Math do?
An AI-powered food journal application that personalizes nutrition guidance based on individual health goals and lifestyle constraints rather than generic calorie-tracking recommendations.
Who founded Napkin Math?
Napkin Math was founded by Jynnie Tang, Manuel Castro, Claire Nord in 2026.
Who are Napkin Math's investors?
Napkin Math's investors include Y Combinator.
Where is Napkin Math headquartered?
Napkin Math is headquartered in San Francisco, US.