Multi-Session Container Tabs makes it easy to open several Firefox Container Tabs at once, all loaded with the same URL. Each tab gets its own completely isolated session with separate cookies, cache, and storage, so they never interfere with each other. Why use it?

Multi-account workflows. Sign into the same service with different accounts, side by side, without logging out and back in.
Development and testing. Quickly spin up isolated sessions to test session handling, caching behavior, or concurrent user scenarios.
Parallel browsing. View the same page in independent contexts without cross-session interference.

Features

Open up to 30 isolated container sessions at once
Configurable delay between tab opens (0 to 10 seconds)
Custom naming prefix for easy tab identification
One-click cleanup to remove all created containers and tabs
Remembers your last-used settings
URL is optional. Open empty containers and navigate later

How it works Click the toolbar icon, enter a URL (or leave it blank), set the number of sessions, and click Open Sessions. Each tab opens in a unique Firefox container with its own cookie jar. When you're done, click the cleanup button to remove everything the extension created. Built on Firefox's native Container Tabs feature using the contextualIdentities API. No data is collected or transmitted. Fully open source.