Microsoft has announced the .NET Framework early access build, which you can download directly from the Microsoft server. This early access build is one of the in-development builds of the next version of the .NET Framework.
Here you can find the link to download the latest version of .NET Framework. Please note that this pre-release build includes improvements in several areas and also includes bugs.
The .NET Framework 4.8 Early Access build can be installed on the following Windows and Windows Server versions: Windows 10 April 2018 Update, Windows 10 Fall Creators Update, Windows 10 Creators Update, Windows 10 Anniversary Update Windows Server version 1709 and Windows Server 2016.
Click here to download latest version of Microsoft .NET Framework 4.8
Before installing this pre-release build, please note that, when you install this .NET Framework 4.8 Early Access build, it will replace any existing .NET Framework 4 and later installation on your machine. This means, all .NET Framework 4 and later applications on your machine will run on the new .NET Framework early access builds after installation.