URL-level vs domain-level blocking: why the difference matters for focus

How domain blocking works

Domain-level blockers work by intercepting requests to specific domain names. When your browser tries to load youtube.com, the blocker sees the domain, checks it against your blocklist, and stops the connection. This can happen at the DNS level (blocking the domain lookup), the hosts file level (redirecting the domain to 127.0.0.1), or the network level (using packet filtering).

The advantage: it's simple, fast, and works across all browsers and apps. The disadvantage: it's all-or-nothing. You can't block YouTube's homepage but allow a specific video. You can't block Reddit's front page but allow a technical subreddit. It's the whole domain or nothing.

How URL blocking works

URL-level blockers inspect the full URL, not just the domain. When your browser tries to load youtube.com/watch?v=abc123, the blocker sees the entire path and query string, checks it against your allowlist, and decides whether to allow or block that specific page.

This requires deeper integration. On Chrome, this typically uses the webRequest API or declarativeNetRequest API to inspect and block requests. On macOS at the system level, this might use a network extension or application firewall that can read HTTP/HTTPS headers.

The advantage: surgical precision. You can block a domain by default and allow specific pages. The disadvantage: it's technically harder to build, which is why most blockers don't offer it.

When domain blocking is enough

If you never need access to blocked sites during focus time, domain blocking works fine. If your blocklist includes purely distracting sites (social media you don't use for work, news sites that eat your time, forums you visit to procrastinate), blocking them entirely is the right call.

Domain blocking also works if you use separate devices or profiles for work and personal browsing. Block everything distracting on your work profile, and keep a separate space for leisure. The all-or-nothing approach is fine when you don't need exceptions.

When URL blocking becomes necessary

URL blocking becomes essential when you need selective access. If you use YouTube for tutorials, Reddit for technical advice, or Twitter for professional networking, you can't afford to block these sites entirely. But you also can't afford to leave them unblocked.

This is where most people get stuck. They try domain blocking, realise they need access to something, unblock the site, and then spend 30 minutes scrolling. They assume the problem is their discipline. The actual problem is the tool.

URL blocking solves this by letting you allow specific pages. Block youtube.com by default, but allow the URLs of videos you need to watch. Block reddit.com, but allow r/programming or specific threads. The distracting parts stay blocked. The useful parts are accessible.

The allowlist workflow

Here's what the workflow looks like in practice. You add distracting sites to your blocklist: youtube.com, reddit.com, twitter.com. These sites are now blocked everywhere (Safari, Chrome, Firefox, system-wide).

Then you find a URL you need to access. Maybe it's a YouTube tutorial, a Reddit thread with a solution to your problem, or a specific Twitter thread. You copy the URL, add it to your allowlist, and refresh. That page loads. Everything else on the domain stays blocked.

When you're done with that page, you close the tab. The next time you absentmindedly try to open YouTube or Reddit, you see the block page. The only way to see more content is to explicitly add more URLs, which creates enough friction to stop the impulse.