Faculty Feature: Karl Ni
by Jussara Oliveira Barbosa, MS in Project Management ’25
Karl Ni thrives where academia and industry intersect, bringing together his expertise as a lecturer at Northeastern University and a leader in machine learning at Etsy. A PhD in Electrical and Computer Engineering from UC San Diego, combined with a BS in Electrical and Computer Science from UC Berkeley, forms the foundation of a career that has spanned elite institutions, groundbreaking research, and impactful education.
At Northeastern University, Ni teaches graduate-level courses in Data Mining and Natural Language Processing. These rapidly evolving fields demand constant innovation to integrate the latest advancements into course materials. “The challenge is delivering content that is both cutting-edge and accessible,” Ni explains. Drawing inspiration from Barbara Oakley’s philosophy of Learning How to Learn, he prioritizes clear, structured teaching methods that connect theory to real-world applications. Karl emphasizes the importance of understanding the ‘why’ behind every concept, ensuring students can apply their learning in practical scenarios. His classes not only equip students with technical skills but also foster critical thinking and problem-solving abilities.
His lectures are filled with examples from his industry experience, illustrating how techniques succeed—and sometimes fail—in practice. This approach not only prepares students for the realities of the field but also equips them for dynamic, impactful careers.
Beyond the classroom, Karl leads the machine learning infrastructure teams at Etsy, where he tackles the monumental challenge of matching 100 million buyers to over 150 million products. His role involves designing recommendation systems that operate at immense scale while remaining cost-effective and innovative. “The mission is to surface the most relevant and engaging products for buyers,” he says. He collaborates with a team of scientists and engineers who innovate at the forefront of recommendation science and multi-modal machine learning, ensuring Etsy delivers exceptional user experiences.
Dr. Ni’s career is defined by transformative projects. During the Obama Administration, he made significant contributions to the President’s Brain Initiative, working across national laboratories and hospitals to investigate the underlying causes of long-term brain disorders. He developed specialized circuits to recognize brain spiking patterns, particularly for veterans suffering from Post-Traumatic Stress Disorder (PTSD), to better understand and address the effects of traumatic brain injuries.
What drew Dr. Ni to Northeastern University was its commitment to diversity and inclusion, exemplified by initiatives like the Align program, which brings professionals from adjacent fields into computer science. “Hiring from diverse backgrounds has been central to my career,” he says, highlighting how talent from fields like Computational Biology, Physics, and Geology, for example, has driven innovation in machine learning. At Northeastern’s Khoury College, he actively fosters an environment where students from varied disciplines and experiences thrive, reflecting the university’s ethos.
Karl’s work at Etsy and his ongoing research efforts often lead to published articles, with many of his insights shared through Etsy’s Data Science and Machine Learning blog, dsml.etsy.com. Additionally, he participates in the SPIE Conference, a forum for applied machine learning, where submissions are welcomed to highlight diverse applications of this rapidly advancing field. “We’re always looking to broaden the variety of perspectives and research that contribute to the conversation,” Ni says. These contributions underscore his dedication to pushing the boundaries of machine learning and fostering community-driven innovation.
Looking to the future, Dr. Ni is captivated by the rapid advancements in generative AI. Beyond foundational models, he sees applications in robotics, medical diagnostics, and cybersecurity as transformative. “It feels like we’re entering a new paradigm,” he notes, emphasizing how generative AI is reshaping venture capital and entrepreneurship with its ability to drive innovation at unprecedented levels.
Despite his technical prowess, Ni maintains a rich life outside the world of algorithms and data. An artist in his free time, he regularly shares his acrylic paintings on social media, ranging from playful dog portraits to serene landscapes. His creative spirit extends to music, where he indulges in ragtime piano, taking inspiration from Scott Joplin. Perhaps most endearing is his dedication to family life, especially during Halloween (his favorite holiday), where his costume-making skills shine – his ingenuity is evidenced by transforming his son into “a literal airplane, not just a pilot in a plane” for the last Halloween.
For those aspiring to grow in their careers, Ni offers this advice: “When you know where you want to go, get organized. A spreadsheet can turn dreams into actionable goals.” He also recommends “The First 90 Days”, a book that helped him navigate the complexities of new roles and organizations.
Through his work at both Northeastern University in Silicon Valley and Etsy, Karl Ni continues to demonstrate the powerful impact one can have when combining academic rigor with industrial innovation. His journey serves as a testament to the value of diverse perspectives, continuous learning, and the importance of maintaining creativity in technical fields.