JSK Shield by Tanay Roy

Most ad blockers ask you to trust them. JSK Shield lets you check. It runs entirely on your device, collects nothing, and its code is open source under the GPL-3.0 licence — so every claim here is verifiable, not marketing.
It blocks ads, trackers and cookie-notice clutter using well-established community filter lists (EasyList, EasyPrivacy and cookie-notice filters), and it stays out of your way:
• No account required. Install it and it works. The core blocker never needs one. • No data collection. No analytics, no telemetry, no tracking of you — there is no server for it to go to. • No paid allowlist. No advertiser can ever pay to have their ads let through. Ever. • Minimal access. Network blocking works without permission to read the pages you visit; you grant per-site access only for extras like hiding leftover ad boxes, the element picker, or fetching a custom list.
What makes JSK Shield different is what happens when something goes wrong. Every other blocker shows you a count. JSK Shield shows you the request that was blocked, the exact rule that blocked it, and the list that rule came from — and gives you a one-click way to allow just that one thing, on just that one site.
There is also an optional Family plan ($3.99/mo, $29.99/yr, or $69 lifetime, 7-day free trial) that adds content-category blocking (Adult, Gambling, Social media), per-child profiles, and scheduled site blocking. Ad and tracker blocking is identical on every plan — Family adds control, it never blocks "better", and there is never a paid allowlist. The Family plan is billed by JSKAPPS, not through the store.
Open source (GPL-3.0). You don't have to trust the privacy claims — you can read them.
Firefox blocks ads/trackers by inspecting requests, so it asks for access to websites when you install it — everything is inspected on your device and nothing about your browsing is sent anywhere.