The maximum number of rule sets is 50, not rules, as your own link clearly and unambiguously states. The actual minimum (not maximum) number of supported rules

The maximum number of rule sets is 50, not rules, as your own link clearly and unambiguously states. The actual minimum (not maximum) number of supported rules is 30,000: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/declarativeNetRequest/GUARANTEED_MINIMUM_STATIC_RULES https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/Web... In reality, Chrome supports over 10x that. And UBOL doesn't even use/need the minimum, sticking to around 17,000. So that's plenty to cover all your websites. Which is why UBOL works perfectly fine in practice.