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The parts of a simple blocker

A simple self-use blocker has three jobs: remember names, notice a visit, and show a calm stop page. This page names the browser tools people meet when they build that for themselves.

Browsers that share one idea

Mozilla Firefox is a browser from the Mozilla project, known for an open extension system and for privacy controls a person can read. Chromium is the open-source browser project behind many desktop browsers, including Google Chrome and Microsoft Edge. An extension written for the shared model can often run in more than one of those browsers, with small differences.

WebExtensions is the name of that shared model. It is a set of agreed files and permissions. A manifest file tells the browser the extension’s name and what it may do. JavaScript is the language used for the small program inside the extension. JavaScript here means page logic, not a promise about winnings. The word is only the programming language.

The three parts

The list

A local file of domain names you chose to pause. Keep it on your device. Do not download a mystery list from a stranger. This site does not publish operator names.

The check

A short JavaScript function that compares the address the browser is opening with the list. A match means stop. No match means leave the page alone.

The message

A plain local page that says the visit was paused. It can link to your own note, or to a public health page you trust. It should not advertise play.

A build order for a personal tool

1. Pick one browser you actually use. Firefox or a Chromium-based browser is enough to learn WebExtensions.
2. Read that browser’s own extension guide before writing files. Official developer docs change less wildly than forum snippets, but they still change. Check the vendor’s current guide.
3. Write a manifest that asks only for the permission to see web requests or to redirect matched sites. Skip unrelated permissions.
4. Store the domain list as data, not as hidden code. You should be able to open the file and read every name.
5. On a match, show your local stop page. On no match, do nothing.
6. Load the extension as a temporary add-on while you test on a harmless site you control, such as a page on your own computer.
7. Only then add the names you personally want to pause.

What not to copy

Do not install an extension that you cannot read. A tool that asks for every site, plus your passwords, is not a modest blocker. OWASP, the Open Worldwide Application Security Project, has long published guidance on not trusting unexplained code. The same caution applies at home.

Do not build a tool that hides itself, disables security warnings, or controls someone else’s device without consent. A personal barrier is for the person who asked for it.

A blocker still leaves a gap

An extension runs in one browser profile. A private window, a second browser, or a phone app can walk around it. Pair the extension with a device control if you need a wider door closed. Read Blocking basics for those places, and Ongoing care for why the list ages.