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Tab: Custom Tabs

Context​

External web apps as a tab in chat rooms and channels — via Add Tab as Website, or by importing a Teams manifest (see Developer documentation).

Setup​

  1. Open Add Tab
  2. Choose Website (or import a Teams manifest)
  3. For Website: enter a valid HTTP or HTTPS URL and optional name
  4. Confirm → the page loads in an iframe

Examples: shared documents, note apps, dashboards, internal tools.

Limitations​

  • Some websites block embedding in iframes (X-Frame-Options / CSP)
  • In such cases you may see an error or blank display
  • Prefer HTTPS; cookies/session may behave differently across domains

Manage​

  • Right-click on tab → Remove or open in new window (bypasses iframe restrictions)

Tab selection and session​

Which tab was last active in a room or channel (conversation/posts, files, custom tab, …) is stored per room/channel for the current browser session and restored when you open it again.

Teams manifest instead of a bare URL​

Developers can import a Teams manifest.json (app store → “Import Teams manifest”). That enables validDomains, optional webApplicationInfo for SSO, and TeamsJS APIs in the iframe. Details: Developer documentation.