ArcMap2SLD 1.3.0 was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. We recommend checking the downloaded files with any free antivirus. This free program is an intellectual property of Aris.
The program lies within Photo & Graphics Tools, more precisely Converters. The most popular version among the program users is 1.3. You can run this free PC program on Windows XP/7/8/10/11 32-bit. ArcGIS_SLD_Converter.exe is the most common filename for this program's installer.
From the developer:
ArcMap2SLD is a free-to-use program that allows you to tansform an ArcMap-project into an SLD document for Web Map Services (WMS). The recent changes are friendly supported by AGI Rijkswaterstaat, Delft. It is implemented in VisualBasic.NET and requires .NET 2.0.
You may want to check out more software, such as GrowCut, Image Converter Wide or PhotoWorker, which might be similar to ArcMap2SLD.