Background: Monitoring trends and perceptions of new nicotine salt-based electronic cigarettes (ECs), like JUUL, is important to identify associations with product experimentation and use. Understanding harm perceptions of these new devices will inform prevention and intervention efforts. The current study assesses perceptions of the absolute harmfulness of JUUL use in addition to comparing it to other tobacco products. Methods: Participants (N = 839, 52% male) reporting ever use of JUUL were recruited from Amazon’s Mechanical Turk from January to March 2018. Respondents completed questionnaire items assessing demographics, co-use of non-JUUL products, JUUL use status (i.e., daily users (10.8%), non-daily users (29.4%), and triers (59.9%)), and JUUL and other tobacco products absolute harm perceptions. Results: Overall, participants rated JUUL as significantly less harmful than all other tobacco products (p < 0.001), except other ECs. Daily JUUL users rated JUUL as less harmful compared to non-daily JUUL users and JUUL triers (p < 0.05). JUUL was rated as more harmful by women compared to men (p < 0.05). Conclusions: Increased frequency of JUUL use was associated with decreased harm perceptions. JUUL was associated with reduced perceptions of absolute harm compared to most other tobacco products, except other ECs. Public health practitioners should develop public health interventions that increase harm perceptions of ECs.