Generally, 9Anime usage is accepted as illegal since it broadcasts unauthorized, copyright-protected material without the consent of the studios, thus infringing on the DMCA laws that most countries, including the US, follow. Even though single watchers seldom get prosecuted, site owners do make money through ads that hurt the makers. Check out 9Anime Alternatives like Crunchyroll's free tier for legal options—it's safe, supports the industry, and provides HD anime with subtitles, thus completely avoiding legal risks.