Rosario M Holsen was born in Washington DC and raised by an immediate and extended family of computer programmers, mathematicians, teachers, and musicians, as well as in a bilingual English-Spanish environment. She first learned to program in elementary school, where she studied Basic and Logo/LogoWriter (now known as MediaWorlds), and over one spring break she taught herself Visual Basic well enough to create a Dungeons and Dragons character generator. When Web 1.0 first launched she spent lunch hours at school building her first web pages using HTML, CSS, and a very basic understanding of JavaScript.

After studying anthropology and history in college she went on to work at her family's craft store in Asheville, NC. Following the slow shuttering of the store due to the Covid-19 pandemic she began training as a web developer, learning Ruby on Rails and expanding her knowledge of JavaScript and its frameworks and thus bringing her life full circle. She still lives in the Blue Ridge with her husband and a variable number of cats, studying languages both computer and human and enjoying her vegetable garden.