Opera Mini was first released in 2005 as a web browser for mobile phones, with the ability to load full websites by sending most of the work to an external server. It was a massive hit, but it started to fade out of relevance once smartphones entered mainstream use.
Opera
Loved that browser, it was so amazing compared to all the half-assed default browsers. Good old days of J2ME.
I also used its bigger brother on Symbian because it rendered the web better, but it was way too memory-hungry.