A week ago, Microsoft finally launched its Chromium-based Edge browser for older versions of Windows, including Windows 7, 8, and 8.1. It was only available from the Canary branch though, which is updated daily. Today, Edge Dev is now available for the older operating systems.
Edge Dev is updated weekly, and that means that it's less likely to break. There's also an Edge Beta branch that's coming soon; that will be updated every six weeks like the stable channel will be. Of course, the stable channel is still a long way off.
You'll get the same builds as users do on Windows 10 and macOS, and they come out on Tuesdays. One feature that you'll find is missing is dark mode, as that automatically matches your system settings. Obviously, there's no native dark mode on Windows 7 or 8.1. Luckily, the Edge team mentioned on the Windows Insider podcast today that it may be adding manual controls.
If you want to check out Edge Dev for older versions of Windows, you can find it here. Just pick the platform you're looking for at the bottom.