Manifest edge_side_panel: pinning a PWA to the Microsoft Edge sidebar

In one line: edge_side_panel is a web app manifest member that opts a PWA in to being pinned to the sidebar in Microsoft Edge; as of the July 2026 update to Microsoft’s own documentation, this feature “is being deprecated” and “will soon no longer be supported.”

This feature is being deprecated

Microsoft’s documentation states: “Update July 2026: This feature is being deprecated; it will soon no longer be supported.” Microsoft points developers to Streamline access to your favorite sites and apps with Sidebar in Microsoft Edge for information about the Sidebar going forward. Treat everything below as a description of a feature Microsoft is winding down, not one to build new dependencies on.

What it does

Adding edge_side_panel to a manifest signals that a PWA can be pinned to the sidebar in Microsoft Edge, where a PWA “can be promoted in the Microsoft Edge sidebar store,” “can detect whether it is running in the Microsoft Edge sidebar or not,” and “defines its own style and layout to provide a user-friendly sidebar experience.”

Requirements and syntax

Microsoft’s docs require the manifest to contain at least name, short_name, description, and icons before adding edge_side_panel:

{
  "name": "PWAmp music player",
  "lang": "en-US",
  "start_url": "/",
  "short_name": "PWAmp",
  "description": "A skinnable music player app to play your favorite mp3 files",
  "display": "standalone",
  "icons": [
    {
      "src": "./favicon-256.png",
      "sizes": "256x256"
    }
  ],
  "edge_side_panel": {}
}

The sidebar’s default minimum width is 376 pixels and is resizable by the user. If an app’s layout cannot support that width, edge_side_panel.preferred_width requests a larger default: “When you define a preferred width in your app’s manifest… the sidebar is automatically resized to your preferred width,” and “Users can resize the sidebar to make it larger than your preferred width, or smaller, up to the 376 pixels minimum width.”

{
  "edge_side_panel": {
    "preferred_width": 480
  }
}

Support

edge_side_panel is a Microsoft Edge-specific manifest member with no other browser implementation documented by these sources, and — per the July 2026 update quoted above — Microsoft now describes it as being deprecated.

Detecting the sidebar at runtime

Microsoft’s docs recommend User-Agent Client Hints over the User-Agent string for detecting whether a PWA is running in the sidebar:

const brands = navigator.userAgentData.brands;
const sidebarBrandInfo = brands.find((b) => b.brand === "Edge Side Panel");
if (sidebarBrandInfo) {
  console.log(sidebarBrandInfo); // { brand: "Edge Side Panel", version: "1" }
} else {
  console.log("App is not running in the Microsoft Edge sidebar");
}

Guard the check with a feature test. This implementation’s own choice, not a Microsoft-documented recommendation, is to treat the absence of navigator.userAgentData as “not in the sidebar” rather than throw:

function isInEdgeSidebar() {
  if (!("userAgentData" in navigator)) {
    // No User-Agent Client Hints support in this browser.
    return false;
  }
  return navigator.userAgentData.brands.some((b) => b.brand === "Edge Side Panel");
}

Microsoft’s docs add that if User-Agent Client Hints cannot be used, developers can instead look for the string Edge Side Panel in the User-Agent header, but recommend against it because “the User Agent string is an outdated mechanism for doing browser detection, and has website compatibility issues.”

Practical checklist

• Do not build a new feature around edge_side_panel — Microsoft’s own docs say it is being deprecated and will soon no longer be supported.
• If already relying on it, plan a migration path; Microsoft points to the linked Sidebar support page for information about the Sidebar going forward.
• Apps pinned to the sidebar via edge_side_panel receive the desktop User-Agent Client Hint by default even if a mobile variant exists; use the Edge Side Panel UA-CH brand to opt a mobile variant back in instead.
• Prefer User-Agent Client Hints over User-Agent string sniffing for sidebar detection, and feature-detect navigator.userAgentData before reading it.

Cross-references

• Manifest icons — one of the manifest members required before adding edge_side_panel
• Manifest display — the display member referenced in the sidebar-only manifest example
• manifest: edge_side_panel support — per-browser support table for this member