# Default Container Handler > Route all external links into a default Firefox container, with graceful handling when Zen Browser reassigns the tab to a different container based on its workspace rules. Canonical page: [https://chrome-stats.com/d/default-container-handler](https://chrome-stats.com/d/default-container-handler) ## Overview - **ID:** `default-container-handler` - **Platform:** Firefox - **Type:** Firefox add-on - **Status:** Available - **Publisher:** Sarcastic Bird - **Category:** tabs - **Daily users:** 2 - **Weekly downloads:** 3 - **Version:** 1.0.1 - **Last updated:** 2026-04-20 - **First published:** 2026-04-17 - **Size:** 11 KB - **Data as of:** 2026-09-19 - **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/default-container-handler/) - **Website:** [https://github.com/sarcasticbird/default-container-handler](https://github.com/sarcasticbird/default-container-handler) ## Description Firefox Multi-Account Containers let you keep browsing contexts isolated, but external links (from other apps, Slack, email, etc.) open in whatever container the active workspace happens to be using. Zen Browser has no concept of a "default workspace," which makes this worse. Default Container Handler fixes this by registering an ext+container: protocol handler. Paired with a URL rewriter like Finicky on macOS, every external link is opened in the container you designate as default (for example, "Personal"). If Zen's workspace rules then reassign the tab to a different container, the extension detects the reassignment and re-opens the link in the correct container, so focus follows the tab instead of flipping back. Setup Install the extension. When prompted, select Default Container Handler as the handler for ext+container: links. Configure Finicky (or any URL rewriter) to rewrite external links into the ext+container:name=<ContainerName>&url=<encoded-url> format. Full setup instructions and a sample Finicky config are on GitHub: https://github.com/sarcasticbird/default-container-handler Privacy This extension does not collect, store, or transmit any data. It only reads tab URLs long enough to route them to the correct container, and creates containers on demand when one doesn't exist. ## Rankings - #64,625 — Overall - #47 — handle - #174 — contain ## Permissions and access ### Permissions - `contextualIdentities` - `cookies` - `tabs` - `webNavigation` ## Safety - **Risk impact:** Moderate risk impact - **Risk likelihood:** Moderate risk likelihood ### Analysis details - Grants access to browser tabs, which can be used to track user browsing habits and history, presenting a privacy concern. - This extension has low user count. Unpopular extensions may not be stable or safe. > Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing). ## Similar extensions and apps - [Open external links in a container](https://chrome-stats.com/d/open-url-in-container) — 1,942 users, 4.90 / 5 - [ContainerGate](https://chrome-stats.com/d/containergate) — 1 users - [Container Redirect](https://chrome-stats.com/d/container-redirect) — 42 users, 5.00 / 5 - [Air Traffic](https://chrome-stats.com/d/air-traffic) — 1 users, 5.00 / 5 - [Multi-Account Containers Tools](https://chrome-stats.com/d/multi-account-containers-tools) — 2 users - [Time Based Default Containers](https://chrome-stats.com/d/time-based-default-containers) - [Containacious](https://chrome-stats.com/d/containacious) - [Ask for Container](https://chrome-stats.com/d/ask-for-container) — 6 users - [Container Forcer](https://chrome-stats.com/d/container-forcer) — 1 users - [Containers Helper](https://chrome-stats.com/d/containers-helper) — 572 users, 4.72 / 5 - [Exclusive Containers](https://chrome-stats.com/d/exclusive-containers) — 6 users, 5.00 / 5 - [Privacy Containers](https://chrome-stats.com/d/privacy-containers) — 1 users --- Source: [Chrome-Stats](https://chrome-stats.com/d/default-container-handler)