Before there was Apple Silicon, before there were Intel-powered Mac computers, there were PowerPC Mac computers. If you still have a PowerPC G4 or G5 Mac, it could potentially use the modern web again, thanks to the PowerFox project.
Apple started transitioning its Mac computers from PowerPC processors to Intel processors in 2006, and most software dropped support for the old architecture within a few years. Firefox 3.6 in January 2010 was the final version with PowerPC support, but the TenFourFox project continued backporting updates and improvements until 2021 .
PowerFox is a new browser project, based on the UXP browser engine and Basilisk browser , both of which are offshoots from old Firefox versions. The goal is to backport as many features and improvements as possible from modern web browsers, which is no small task on these decades-old versions of Mac OS X.
PowerFox has an "up-to-date JavaScript engine," color emoji support, WebGL, and TLS 1.3, so it can load many modern websites with minimal errors. It also still has NPAPI plugins support, so you can use Adobe Flash Player or other old plugins—you're not going to run into much Flash content on the modern internet, though.
This isn't just a project for PowerPC Mac computers. It works on both Intel and PowerPC processors, across Mac OS X 10.5 Leopard and Mac OS X 10.6 Snow Leopard. The PowerPC version is a beta version, while the Intel version should be more stable.
An announcement post explained, "PowerFox for PPC is not a derivative of TenFourFox. Rather, it is a brand-new browser for PowerPC, built from the same codebase as the 10.6 Intel variant. To refresh your memory, this brings a modern web engine (UXP) with excellent support for the modern internet, with features such as OpenGL acceleration, coloured emoji, modern HTML/CSS/JavaScript support, container tabs, language packs, video codecs (no need for an "enabler"), and much more."
There are some catches. You need a G4 or G5 processor, and it needs to be at least 1 GHz for video playback. There's also no Just-in-Time (JIT) JavaScript engine yet on PowerPC, so many websites are going to be slow, especially web apps.
I don't have a G4 Mac set up right now, but I tried out a few websites in the PowerPC version running under Rosetta emulation on my Snow Leopard Mac Mini. Besides the slow performance (due to the extra emulation and lack of JIT), it seemed to render modern sites like Google, BBC.com, and MacRumors with minimal issues.
It's worth noting that older Intel Macs aren't quite as limited with web browser selection. Firefox 48 from 2016 was the final release for Snow Leopard, and Firefox 68 from 2019 was the last update for Mac OS X 10.7 Lion. The Pale Moon browser still supports OS X 10.7 Lion. If dual-booting to Windows 10 or a modern Linux distribution is an option with Boot Camp, you could potentially run a modern web browser on those machines—it will just be a slow experience.
You can download PowerFox from the project's official website. You'll still want to keep a copy of TenFourFox or old Firefox installed, though, at least until JIT support arrives.
Source: PowerFox blog
