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Current State of Firefox version

Back Philipp Written by Philipp

Firefox

Bookmark Sidebar is officially available for Google Chrome and Microsoft Edge. Both of these browsers are based on Chromium, which means they share the same underlying engine and most technical behavior.

Even though their user interfaces look different, the core systems are the same: page rendering, JavaScript execution, and, most importantly for this extension, the extension APIs.

Browsers expose these APIs so extensions can interact with features like bookmarks. Through the required permission, Bookmark Sidebar can access your bookmark data, read the full bookmark tree, and perform actions such as creating, editing, moving, or deleting bookmarks.

Firefox Compatibility

Firefox is built on a different engine and uses its own implementation of the WebExtensions system. While there has been ongoing effort to align Firefox with Chromium’s extension standards, full compatibility is still incomplete.

The long-term goal is partial alignment with Chromium’s Manifest V3 model, which would make porting extensions between browsers much easier.

What is Manifest V3?

Manifest V3 is the current generation of the Chrome extension platform. It replaces older parts of the extension system (Manifest V2) with a more restricted model. Manifest V3 is partly motivated by limiting the capabilities of content-blocking extensions, especially ad blockers.

Key changes include:

  • A shift from background pages to service workers
  • Replacement of blocking request APIs with declarative rules (declarativeNetRequest)
  • Stronger privacy and security constraints
  • More limitations on runtime code execution and network interception

This shift has been widely debated in the developer community. Migrating to Manifest V3 required significant changesa and engineering effort just to maintain feature parity under the new constraints.

For a broader technical and critical perspective, this article provides a useful overview of the concerns raised at the time:

https://www.eff.org/de/deeplinks/2021/12/googles-manifest-v3-still-hurts-privacy-security-innovation

Current Situation

The main blocker for a Firefox version of Bookmark Sidebar is that Firefox does not yet fully support the Manifest V3 features required by the extension.

Relevant tracking issue: https://bugzilla.mozilla.org/show_bug.cgi?id=1578284

These changes have been in progress for a long time, but progress has been slow and not very visible.

I check the status every few months to see whether there are meaningful updates or signs of active development. At the moment, it still appears that this area is not a current priority.

What This Means in Practice

Without the required APIs, a Firefox version cannot be created as a straightforward port. It would require a separate implementation with different architecture and significant workarounds for missing functionality.

That would effectively mean maintaining two independent codebases, which is not realistic for a side project built alongside full-time work.

Outlook

For now, I’m simply monitoring the situation. If Firefox eventually completes the necessary Manifest V3 support in a stable and usable form, I would revisit this and likely work on a proper Firefox port.