In the white paper and website, we talk about opt-in for anything that does local M/L on your local data (which his the data already computed on-device by all browsers today).

(From replies to your comment I feel the need to add: The first thing to do before jumping to "Everyone is stupid except me" (H. Simpson) is read carefully and consider what is proposed on its face. ;-)

Baseline Brave doesn't do anything with ads except block third party trackers and ads. We offer opt-in fingerprinting protection and script blocking too, and we will work to enable fingerprint defense by default. This baseline won't change, it's the starting condition for opt-in methods which users may choose to help support sites.

The first and cleanest opt-in method is already in Brave on laptop/desktop. Go to Preferences / Payments to fund a wallet so you can auto-micro-donate to your top sites as calculated locally (no remote tracking) over 30 days of uptime. At the end of the 30 day period, using VPN for IP address masking and a ZKP based on https://anonize.org/, Brave sends zero-knowlege proof "votes" for the candidate sites you browsed. You can adjust or turn off any sites you don't wish to support.

We're building on this beta "Brave Payments" system to efface bitcoin from users' view, and eventually from publishers. But right now publishers who have money due to them can come and get it by verifying they own their domain (akin to the ACME challenge-response protocol pioneered by LetsEncrypt), at https://publishers.brave.com/.

We don't expect donors to make up for lost ad revenue at scale, which is why we are working on basicattentiontoken.org and an opt-in client component to mine your data on-device, no signals out. Note your data includes you queries to search engines -- these belong to you and they form hot intent signals from you should benefit materially, and not just in quality of results -- in all economics based on search plus browsing.

Brave is all auditable open source, all non-baseline browser options are opt-in. Sorry, gotta repeat given the tendency to miss or misstate this.

The opt-in M/L component can predict a set of keywords to match against an offer and ad catalog downloaded to each opted-in user's device. That catalog has only edge-cache URLs with small keyword sets per URL.

Upon finding the best match at the best time, you'll get an offer or ad. We are planning to let you choose several channels: fullscreen video, chatbot on a messaging app, even one per day email (some people prefer this). Only with publishers who partner with us and want to see how this system can work on their third party ad slots in which we block ads will we, with user opt-in as well as publisher, see if we can fill empty space.

Instead of shotgunning thousands of websites to try to reach users who are poorly tracked by today's cookies, user-ids on mobile, and fingerprinting, we believe a private promotion system can show much better performance in all dimensions (opt-in user happiness, data and battery use, conversion for ad buyers, yield for ad space sellers if they are in the loop).

As Joe Marchese (TrueX, now Fox -- Joe encourages his staff to install and use adblockers) has pointed out, today's digital ad system wastes money and loses users by spray-and-pray tactics, instead of finding the right place and time to give you marketing information you might actually want. Again and I'll stop repeating it, this is all only if you opt in. But, if you do, then you get a revenue share in BATs. Brave's cut will be same or smaller, that's a brand promise. If the ad places in a channel you control (fullscreen video, chatbot, email), the bulk of the revenue will go to you.

Anyway, that's what we are building.

All BAT-certified apps (BAT is for more than Brave, e.g., other browsers, "readers", games, messaging apps), will have to conform to rules we are prototyping in Brave. Conformance will be built into the cryptographic protocols, plus rate-limits and other defenses, so cheating and fraud will be very hard. More on this over time as we launch BAT and build out the full prototype in Brave.