Caption This

A frosh’s company makes kids’ flicks more accessible.

March 2024

Reading time min

A woman signing "I love you"

Photo: Ananya Navalle, ’25

When Mariella Satow’s high school closed during the COVID-19 lockdown, she took the opportunity to enroll in an American Sign Language (ASL) class. 

“I immediately fell in love with it,” she says. Several of her relatives have hearing loss, but none had learned to sign. 

Satow, ’27, searched for free educational resources that would help her gain proficiency in ASL, but she found few. In doing so, however, she learned about the challenges facing people who are deaf or hard of hearing, especially children—from the risk of language deprivation at a critical time in their development to the inaccessibility of TV shows and movies that could expose them to language in the environment. Closed captioning, while widely available, is inaccessible to kids who sign but don’t yet read, as well as to readers who find fast-paced dialogue hard to follow. To help bridge this communication gap, Satow launched SignUp Captions, a free browser extension that provides overlays with sign language interpretation for streaming content on Disney+ and Netflix.

Closed captioning, while widely available, is inaccessible to kids who sign but don’t yet read.

Working in close collaboration with the Deaf community, Satow built SignUp on a shoestring. “At the beginning, my budget was so small,” she says. “I was using money I had made dog walking.”

SignUp landed in the spotlight in August 2021 with its launch of ASL overlays for Moana, Zootopia, and The Incredibles on Disney+. Surprised by its success, Satow took a gap year to develop the company before matriculating at Stanford. Today, captioning is available for more than 100 titles. Interpretation is available in American, British, and Indian sign language, with Auslan (Australian Sign Language) coming soon. 

Satow, whom Forbes recently named to its 30 Under 30 list, points to the importance of showcasing the talent within the Deaf community. SignUp is currently refilming its overlay for Moana, set in ancient Polynesia, with a Pacific Islander interpreter; the interpreter for Ratatouille, set in a busy Parisian restaurant kitchen, is both deaf and a chef. “The interpreters are definitely the unique value of SignUp,” she says.

Rachel Kolb, ’12, MA ’13, is a junior fellow in the Society of Fellows at Harvard and a former editorial intern for Stanford. Email her at

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