Browser Extensions

A poketto.me Firefox user recently pointed out that Firefox on Android also supports browser extensions– but that the poketto.me extension didn’t appear on Mozilla’s Add-Ons page there. Turns out: Any modern browser extension built on the standard APIs (Chrome, Firefox, Edge) can also run in Firefox on Android. But when publishing, you have to explicitly test and target Android. Technically, the extension “just works”—as long as you’re not doing anything exotic with the APIs. But aesthetically, there’s one big caveat. ...

The other week, I was building a neat little feature for the poketto.me browser extensions (Chrome, Firefox, and Edge): when you save a web page, the extension should capture not just the URL, but the entire content you’re looking at in that moment. 🤨Why does this matter? If you’re signed in on a page (say, with your New York Times subscription), poketto.me can capture the full article — just as you, the paying subscriber, see it. Otherwise, poketto.me tries to fetch the article in the background… but it will run straight into the paywall (see TIL #59). ...

I hadn’t actually planned to build a Firefox extension for poketto.me. But among the first wave of “Pocket Converts” — users who turned to poketto.me after reading about it as an alternative to Pocket — several asked for a Firefox extension. So, I decided to do a quick technical feasibility check. As it turns out: The Chrome extension works in Firefox without a single code change! Apparently, there are a few APIs that Firefox doesn’t support (see: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Browser_support_for_JavaScript_APIs), but luckily, I didn’t rely on any of those. ...

To my surprise, building a Chrome Extension is technically quite straightforward. You need: A bit of HTML (the popup UI) A bit of JavaScript (your logic) And a $5 one-time fee to publish in the Chrome Web Store The Chrome Extensions API is pretty minimal, but it covers all the basics: ✅ You can persist data (e.g. auth tokens) ✅ You can query open tabs, grab the current URL ✅ You can even inject JavaScript into pages — though this last bit triggers stricter review from Google, especially if you request broad access (like "<all_urls>"). ...