Firefox

Begs? Bad take. It's the developer's full time job to make those two extensions. They don't materialise out of thin air, someone has to dedicate themself to developing it, hosting the servers which store and send the information, managing the community around them, fixing bugs. That stuff isn't free. The servers alone cost hundreds of dollars per month. If you value the utility that it gives you then paying a small amount for the server cost and the developer's time is completely fair.

edit: oh and also dearrow is usable entirely for free. The payment is basically optional.