Today Microsoft announced that the Chromium Microsoft Edge extension store is open to all developers, and any developer can submit their own extensions in the Partner Center Developer Dashboard. Since the new Microsoft Edge browser is based on the Chromium browser, most Chromium extensions can run without any adjustments. Microsoft also provides some exclusive APIs for Edge, which developers can learn about here.
Microsoft also announced that it will no longer accept new extensions for Microsoft Edge Legacy (EdgeHTML-based) starting today (December 17). However, developers can continue to provide maintenance updates for existing extensions.
We recommend you prioritize building new extensions for the new Chromium-based Microsoft Edge, and continue to support your existing EdgeHTML-based extensions to ensure a quality experience for active users.
Developers who have given consent for Microsoft to migrate their EdgeHTML extension listings to the new Microsoft Edge should begin to see their extensions available in the new Addons store experience in Microsoft Edge. If you publish an EdgeHTML extension and have not received any communication regarding its migration or are unsure of its status, please contact us at ExtensionPartnerOps@microsoft.com.