How To Redeem
Capital One is offering a limited time bonus of $20 just for installing their browser extension and leaving it on for 90 days. It says the requirement besides time is using it as you normally would. So I recommend clicking through some offers a few times. They also sometimes have great cash back boosts like Adidas earlier that was 40% back.
Full terms:
Create an account and verify your email.
Add the free shopping savings tool with full permissions – then use it for 90 days to enjoy free coupons and rewards at 100K stores.
Note: Not sure how they determine regular use or if they will even try but you should definitely use it a couple of times even if you don’t actually purchase something through it.
You can get $20 in shopping rewards!
You do not need to be a Capital One customer or account holder to use Capital One Shopping. Capital One Shopping is free to everyone.

This offer is available only for Refer-ees who are new Capital One Shopping users (real people who do not have [and have not previously had] a Capital One Shopping User Account). For either the Referrer or Refer-ee to be eligible for a referral bonus, the Refer-ee must install either the Shopping desktop or mobile extension in their primary browser with full permissions, and on a device in which the extension has never previously been installed. The Refer-ee must install the Shopping extension within 7 days of creating a Shopping User Account using a referral link. The Refer-ee must then regularly use the Shopping extension and shop as they normally would, on their primary browser and with full permissions granted, for 90 days following the installation date. The referral bonus will be automatically applied to the relevant accounts within 30 days after the Referrer and Refer-ee have satisfied all requirements. Uninstalling the Shopping extension or changing its permissions at any time during the trial period will prevent both the Referrer and Refer-ee from receiving a referral bonus. To be eligible for this offer, both the Referrer and Refer-ee must be located in and reside in the United States.

