TenFourFox: A great web browser based on FireFox ESR 45. Make sure to pick the version for your processor: G3: Get the G3/G5 version G4: 7400: Get the 7400 version -- 7450: Get the 7450 version. The PPC 7450 has a slightly longer pipeline. The G4 also adds AltiVec(TM), a powerful vector processor.
Classilla is great for really old Macs.
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