19 October 2021
There are many internet browsers available for Classic Mac OS systems. Almost all modern websites are inaccessible to early Mac OS, and likely won't render correctly or load at all on any of the browsers listed below. This is due to modern web development advancements which aren't present in the browsers, and are no longer updated. Most websites are also served via the HTTPS protocol rather than the HTTP protocol expected by these browsers. For further reading, see HTTPS and why it's a problem for early Mac OS.
Websites that have been designed with older browsers in mind, or websites that are still around from the early 90's - 2000s are accessible on these browsers.
There has been an effort to compile a directory of modern, and existing website that are accessible to older internet browsers. Visit the directory at Sloop Web Directory.
Classilla was the last web browser that had recent updates and was maintained every couple of years until 2021, by Cameron Kaiser. The next best browser for Mac OS in terms of website compatibility/standards supported is Internet Explorer 5.