Purpose The goal was to evaluate the content, quality, and readability of the information available about clear aligner treatment on the Internet. Materials and methods The search terms "aligner," "clear aligner," and "Invisalign" (Align Technology, Tempe, AZ, USA) were analyzed in three search engines (Google [Google LLC, Mountain View, CA, USA], Bing [Microsoft, Redmond, WA, USA], and Yahoo [Yahoo, Sunnyvale, CA, USA]). The first 50 websites for each keyword in each search engine were screened. Duplicate websites, advertisements, links to scientific articles, videos, and other irrelevant websites were excluded. The quality of the remaining websites was analyzed using the DISCERN and Journal of American Medical Association (JAMA) benchmark instruments together with the Health on the Net code (HONcode, Health On the Net Foundation, Geneva, Switzerland). The readability of the websites was evaluated by the Flesch Reading Ease Score (FRES) and Flesch-Kincaid Grade Level (FKGL). Statistical analyses were performed by one-way analysis of variance, Kruskal-Wallis and Fischer's exact tests, with p < 0.05 accepted to be statistically significant. Results Among 111 evaluated websites, most belonged to multidisciplinary dental clinics (n = 49; 44.2%), followed by aligner companies (n = 26; 23.4%), orthodontists (n = 26; 23.4%), and professional organizations (n = 10; 9%). The mean DISCERN score (sections 1 and 2) for all websites was 29.95/75. The average FRES and FKGL were 55.77 and 9.74, respectively. Professional organization websites had significantly higher DISCERN scores than others (p < 0.001), and together with multidisciplinary dental clinic websites, they showed better compliance with JAMA benchmark criteria. Professional organization websites' FRES and FKGL were also higher than other websites (p > 0.05). Conclusions Overall, the quality of web-based information about clear aligners was poor and the readability of the data was insufficient. Websites presenting high-quality data with better readability are needed for potential aligner patients.