Container Redirect

Automatically choose a Firefox Container when visiting selected domains.

Container Redirect is a lightweight Firefox extension that prompts you to choose a Firefox Container whenever you navigate to a domain you've configured.

It is designed for people who use Firefox Multi-Account Containers and want certain websites to always be opened in a specific container without having to manually switch containers first.

Features

Domain-based container prompts Configure any number of domains that should trigger the container picker.
Native Firefox Containers Uses Firefox's built-in contextual identities rather than implementing a separate container system.
One-click container selection Displays your available containers directly in the page so you can choose where the site should open.
No forced container mapping You decide which container to use every time a watched domain is visited.
Persistent domain configuration Watched domains are stored using Firefox extension storage and survive browser restarts.
Domain normalization Inputs such as https://www.example.com/ are normalized to example.com.
Redirect-chain handling The extension avoids repeatedly displaying the picker during multi-step redirects such as authentication and SSO flows.
Same-document navigation protection SPA navigation using history.pushState() / replaceState() does not unnecessarily trigger the picker again.
Privileged-page navigation fallback Includes a secondary navigation safety net for cases where Firefox does not expose a navigation through the normal request interception path.
Session-scoped navigation exemptions Once the extension has opened a watched domain in a selected container, that tab is not immediately intercepted again for the same domain.
Minimal and local Configuration is stored locally in the browser. The extension does not require a remote backend.

How It Works

The extension watches top-level HTTP and HTTPS navigations.

When a request matches one of your configured domains, Container Redirect interrupts the normal navigation and presents a container selector.

For example:

You configure:

    github.com
    chatgpt.com
    example.com

You visit:

    https://chatgpt.com/

Container Redirect:

    ┌─────────────────────────────────┐
    │ Open chatgpt.com in:            │
    │                                 │
    │  ● No Container                 │
    │  ● Personal                     │
    │  ● Work                         │
    │  ● Development                  │
    │                                 │
    │              ✕ Cancel           │
    └─────────────────────────────────┘

After you choose a container, the target URL is opened in a new tab using that container's cookieStoreId.

This makes it possible to keep accounts, cookies, sessions, and browsing contexts separated using Firefox's native container system.

Installation

From Firefox Add-ons

https://addons.mozilla.org/en-US/firefox/addon/container-picker/

Usage

After installing the extension:

1. Open the extension popup

Click the Container Redirect toolbar icon.

2. Add a watched domain

Enter a domain such as:

github.com

Then click Add.

The input is normalized automatically, so these will resolve to the same domain:

github.com
www.github.com
https://github.com/
https://www.github.com/some/path

3. Visit the domain

Navigate to the configured domain normally.

Container Redirect will present a container picker.

4. Select a container

Choose one of your Firefox Containers.

The destination will then open in the selected container.

5. Remove a domain

Open the extension popup and click the × button next to a watched domain.

Example Use Cases

Separate work and personal accounts

Watch:

google.com
github.com
slack.com
notion.so

Then choose your Work container whenever one of those domains is opened.

Force authentication into a dedicated container

Watch:

accounts.google.com
login.microsoftonline.com
auth.example.com

This can help keep authentication cookies isolated from your normal browsing environment.

Keep AI tools isolated

Watch:

chatgpt.com
claude.ai
gemini.google.com

Then open them inside a dedicated AI or Work container.

Architecture

Container Redirect is intentionally small and dependency-free.

┌──────────────────────────────┐
│         Firefox Browser      │
└──────────────┬───────────────┘
               │
               ▼
       ┌─────────────────┐
       │  background.js  │
       │                 │
       │ Domain matching │
       │ Navigation      │
       │ Redirect logic  │
       │ Container APIs  │
       └───────┬─────────┘
               │
        ┌──────┴───────┐
        ▼              ▼
 ┌─────────────┐  ┌─────────────┐
 │  popup.js   │  │ content.js  │
 │             │  │             │
 │ Domain list │  │ In-page UI  │
 └─────────────┘  └──────┬──────┘
                         │
                         ▼
                  ┌─────────────┐
                  │  picker.js  │
                  │             │
                  │ Container   │
                  │ selection   │
                  └─────────────┘

Main files

File	Purpose
`manifest.json`	Extension metadata, permissions, scripts, icons, and Firefox configuration
`background.js`	Core navigation interception and container orchestration
`popup.html`	Extension popup UI
`popup.js`	Watched-domain management
`popup.css`	Popup styling
`content.js`	Injected container-selection banner
`content.css`	In-page prompt styling
`picker.html`	Fallback/full-page container picker
`picker.js`	Container picker logic
`picker.css`	Picker styling
`icons.js`	Firefox container icon rendering
`background.js`	Navigation, redirect, exemption, and message routing
`icons/`	Extension icons

Navigation Flow

The normal flow looks like this:

User navigates to a URL
          │
          ▼
   Is it HTTP/HTTPS?
          │
          ▼
 Does the domain match
 a watched domain?
       │       │
      No      Yes
       │       │
       ▼       ▼
   Continue   Check exemptions
   normally       │
                  ▼
          Intercept navigation
                  │
                  ▼
        Show container picker
                  │
        ┌─────────┴─────────┐
        ▼                   ▼
   User cancels       User selects
                         container
                             │
                             ▼
                 Open target in new tab
                  using cookieStoreId

Important Edge Cases

Container Redirect contains additional logic specifically to avoid false-positive prompts.

Redirect chains

Some websites perform multiple HTTP redirects before reaching the final destination.

The extension tracks redirect chains so that one navigation does not repeatedly trigger the container picker.

Single-page applications

Modern websites frequently change the URL using the History API without performing a full page navigation.

Container Redirect tracks:

history.pushState()
history.replaceState()

and fragment navigation to prevent these URL changes from being mistaken for a fresh visit.

Refreshes and same-domain navigation

Once a tab has been assigned to a container for a watched domain, the extension keeps that tab/domain combination exempt while the tab remains open.

This prevents a normal refresh from immediately reopening the picker.

Privileged Firefox pages

Some Firefox-origin pages such as:

about:newtab
about:blank

do not always behave like normal web pages from the perspective of webRequest.

Container Redirect therefore includes a tabs.onUpdated safety net for navigation events that may bypass the normal request interception path.

Permissions

The extension requests the following Firefox permissions:

contextualIdentities
cookies
webRequest
webRequestBlocking
webNavigation
tabs
storage

It also declares:

<all_urls>

Why these permissions are required

Permission	Reason
`contextualIdentities`	Read Firefox Containers and obtain their `cookieStoreId` values
`cookies`	Required for container/cookie-store integration
`webRequest`	Detect navigations to watched domains before they complete
`webRequestBlocking`	Cancel a matching navigation so the extension can redirect it into a container flow
`webNavigation`	Detect same-document navigation and improve navigation handling
`tabs`	Create, update, inspect, and close tabs
`storage`	Persist watched domains and session navigation state
`<all_urls>`	Allow the extension to inspect navigations to arbitrary user-configured domains

The extension does not currently require a remote server or third-party API.

Privacy

Container Redirect is designed to operate locally inside Firefox.

Watched domains are stored using:

browser.storage.local

Temporary navigation state is stored using:

browser.storage.session

The extension does not need to send browsing data to an external service.

The manifest also declares no required data collection:

"data_collection_permissions": {
  "required": [
    "none"
  ]
}

For complete privacy/security claims, review the current source code and Firefox extension manifest before publishing.

Compatibility

The extension is configured for:

Firefox 115+

as specified by:

"strict_min_version": "115.0"

It relies on Firefox-specific APIs such as:

browser.contextualIdentities

so Firefox is the primary target browser.

Roadmap

Potential future improvements include:

Persistent domain → container rules
Optional default containers per domain
Wildcard/subdomain rules
Import/export of configuration
Better domain validation
Context-menu integration
Keyboard shortcuts
Firefox Add-ons publishing
Automated extension testing
More granular per-domain behavior
Optional "always use this container" mode
Improved first-run onboarding

License

This project is licensed under the MIT License.

Acknowledgements

Built for Firefox users who rely on Firefox Multi-Account Containers.

Uses Firefox WebExtensions APIs and the Firefox contextualIdentities API.

Disclaimer

Container Redirect is an independent open-source project and is not affiliated with or endorsed by Mozilla.

Firefox and Firefox Multi-Account Containers are trademarks of Mozilla.

Navigation Menu

Repository files navigation

Container Redirect

Features

How It Works

Installation

From Firefox Add-ons

Usage

1. Open the extension popup

2. Add a watched domain

3. Visit the domain

4. Select a container

5. Remove a domain

Example Use Cases

Separate work and personal accounts

Force authentication into a dedicated container

Keep AI tools isolated

Architecture

Main files

Navigation Flow

Important Edge Cases

Redirect chains

Single-page applications

Refreshes and same-domain navigation

Privileged Firefox pages

Permissions

Why these permissions are required

Privacy

Compatibility

Roadmap

License

Acknowledgements

Disclaimer

About

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Contributors

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Name		Name	Last commit message	Last commit date
Latest commit History 4 Commits
icons		icons
.gitignore		.gitignore
README.md		README.md
background.js		background.js
content.css		content.css
content.js		content.js
icons.js		icons.js
manifest.json		manifest.json
picker.css		picker.css
picker.html		picker.html
picker.js		picker.js
popup.css		popup.css
popup.html		popup.html
popup.js		popup.js

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Repository files navigation

Container Redirect

Features

How It Works

Installation

From Firefox Add-ons

Usage

1. Open the extension popup

2. Add a watched domain

3. Visit the domain

4. Select a container

5. Remove a domain

Example Use Cases

Separate work and personal accounts

Force authentication into a dedicated container

Keep AI tools isolated

Architecture

Main files

Navigation Flow

Important Edge Cases

Redirect chains

Single-page applications

Refreshes and same-domain navigation

Privileged Firefox pages

Permissions

Why these permissions are required

Privacy

Compatibility

Roadmap

License

Acknowledgements

Disclaimer

About

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