> ## Documentation Index
> Fetch the complete documentation index at: https://extension.js.org/llms.txt
> Use this file to discover all available pages before exploring further.

# September 2026: a showcase page, Deno and Bun

> What shipped in Extension.js during September 2026: the showcase page, Deno and Bun as runtimes, Zen and Floorp as browser targets, sharper manifest prefixes, a content script reload that runs one copy, and the rspack pin.

<Update label="September 2026" description="October 9, 2026" tags={["roundup"]}>
  September was two things: a page that shows what people ship with Extension.js, and a run of releases that took the CLI from [4.1.18](https://github.com/extension-js/extension.js/releases/tag/v4.1.18) to [4.1.30](https://github.com/extension-js/extension.js/releases/tag/v4.1.30).

  ## The showcase

  [extension.js.org/showcase](https://extension.js.org/showcase) is live. Five extensions, all shipped and all in the stores: [Better Lyrics](https://chromewebstore.google.com/detail/effdbpeggelllpfkjppbokhmmiinhlmg), [Star Citizen Box](https://chromewebstore.google.com/detail/gocnjckojmledijgmadmacoikibcggja), [Simple Virtual Keyboard](https://chromewebstore.google.com/detail/cjabmkimbcmhhepelfhjhbhonnapiipj), [Better Trello](https://chromewebstore.google.com/detail/dnhdnenpngcecekbhklemaidbdpibiae), and [Send to PocketBook](https://chromewebstore.google.com/detail/mockojkggpmpjlajehofiljbbbaoppdj).

  The bar is deliberate. A card needs a real store listing and at least a hundred users, and no card shows a user count, so nothing on the page rots. A weekly job proposes candidates and [a person adds them](/showcase#add-your-project).

  ## Two more runtimes

  [4.1.20](https://github.com/extension-js/extension.js/releases/tag/v4.1.20) added Deno. [`deno run -A npm:extension@latest`](/docs/languages-and-frameworks/deno) runs dev and build, and both are covered by CI.

  [4.1.21](https://github.com/extension-js/extension.js/releases/tag/v4.1.21) added Bun. [`bunx --bun extension@latest dev`](/docs/languages-and-frameworks/bun) works on Bun 1.2 or newer, and an older Bun gets one line pointing at the Node.js path.

  ## More browsers by name

  [4.1.26](https://github.com/extension-js/extension.js/releases/tag/v4.1.26) added [`--browser=zen`](/docs/browsers/running-other-browsers#run-a-fork-by-name) and [`--browser=floorp`](/docs/browsers/running-other-browsers#run-a-fork-by-name). They find a stock install on macOS, Windows, and Linux, the same way Waterfox and LibreWolf already did.

  [4.1.29](https://github.com/extension-js/extension.js/releases/tag/v4.1.29) fixed a bug there too. `--browser=brave`, `opera`, `vivaldi`, and `yandex` could open the managed Chrome while the terminal named the fork. Each one runs its own app now, and a check launches every browser and reads which app is really running.

  ## One manifest, sharper

  Since [4.1.19](https://github.com/extension-js/extension.js/releases/tag/v4.1.19), `chrome:` and `edge:` mean that one browser, not the whole Chromium family. [`chromium:`](/docs/features/browser-specific-fields) is the family. That made a new failure possible, a manifest that scopes every `manifest_version` to a vendor, so 4.1.21 refuses that build and names the fix.

  Production Edge builds now drop a top-level `key`, because [Edge Add-ons](/docs/publishing/package-for-the-stores) rejects any manifest that contains one. That came from the maintainer of [Better Lyrics](https://github.com/better-lyrics/better-lyrics), who was stripping it by hand after every build.

  ## Reloads

  In dev on Chrome and Edge, saving a content script used to leave the old copy running next to the new one. [4.1.25](https://github.com/extension-js/extension.js/releases/tag/v4.1.25) [registers dev content scripts at runtime](/docs/implementation-guide/content-scripts#development-behavior), so an edit runs exactly one copy, in the open tabs and in every new page. Editing an HTML page now refreshes that page alone.

  ## One bug worth naming

  A fresh install of [4.1.18](https://github.com/extension-js/extension.js/releases/tag/v4.1.18) through [4.1.23](https://github.com/extension-js/extension.js/releases/tag/v4.1.23) could pull a newer [rspack](https://rspack.rs) than the one we test against, and every page with a linked stylesheet threw on load. [4.1.24](https://github.com/extension-js/extension.js/releases/tag/v4.1.24) pins the bundler and adds a build spec that guards the shape. If you are on any of those versions, upgrade.

  ## Also

  [`extension create --template transformers-js`](/docs/languages-and-frameworks/webassembly#transformers-js) scaffolds a side panel that classifies text on device, modeled on [Hugging Face's own extension sample](https://github.com/huggingface/transformers.js-examples/tree/main/browser-extension). [`extension build --browser=opera`](/docs/commands/build#readable-output-for-opera-add-ons) ships code without minification, which Opera Add-ons asks for in review. Extension.js is now listed on the [Preact integrations page](https://preactjs.com/about/libraries-addons/), [awesome-vue](https://github.com/vuejs/awesome-vue#scaffold), and [awesome-shadcn-ui](https://github.com/birobirobiro/awesome-shadcn-ui#boilerplates--templates).

  October is already at [4.1.33](https://github.com/extension-js/extension.js/releases/tag/v4.1.33). One sidebar key builds for every browser, Safari dev runs leave your own Safari alone, and the sidebar starters read the open tab. More on that next time.

  Cezar Augusto<br />
  Creator and Lead Developer, Extension.js
</Update>


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