Firefox 3 shipped in June 2008 with a wide range of improvements to performance, stability and security, plus several new user-facing features. This was a recap of the design work the Mozilla community published before the release — and, having lived with the browser ever since, a look at which of those ideas survived.
What shipped in Firefox 3
Places — bookmarking, tagging and history. Places was the new infrastructure for storing bookmarks, history and page metadata, replacing the old flat bookmarks.html file with a single SQLite database. It gave us the unified star button, tags and smart folder views. The design mockups promised everything from “Web 2.0-esque tagspaces” to annotation extensions; what landed was quieter, but the SQLite backbone is still under Firefox’s bookmarks and history today.
Malware protection. Like Firefox 2 blocked phishing sites, Firefox 3 started blocking sites known to distribute malicious software, in coordination with Google’s Safe Browsing list. That one shipped as promised and still runs in every modern browser.
Content handling. The plan was a unified interface for deciding what happens with downloads, feeds and protocol handlers, replacing a patchwork of per-MIME-type dialogs. The download manager got its facelift; the grand unified UI never fully materialized.
Microformat detection. Endless UI experiments — changing the cursor over microformatted content and so on. It never shipped, and microformats themselves quietly lost to JSON-LD, schema.org and whatever else crawlers actually parse.
Looking back
The 2007-era disclaimer is fun to reread: Mozilla claimed it was “only interested in adding features that are universally useful, and have no impact on performance.” The principle didn’t survive contact with the following decade — but Firefox 3 itself largely kept it.
The real story of the release was the extension ecosystem, though. The compatibility break left Firebug, FireFTP and most popular themes broken at launch. It was a gentle preview of what the Firefox 57 (Quantum) rewrite would later do to extensions — only much harsher. “Hope this changes soon,” I wrote at the time. It did, eventually.