3

I recommend Paint.NET with the Seamless Helper Plugin (direct download). After installation of Paint.NET, you need to copy that DLL file to C:\Program Files\paint.net\Effects\SeamlessHelper.dll. Here's how easy it is: Create a new picture with even pixel length. I use 200x200 px here. Draw something on the center horizontal and vertical lines, like so: ...


2

IrfanView is a free image-editing tool with a many batch-operation options, as shown below, and the JPEG save dialog includes the progressive option. It is a Windows application, but runs well under wine in Linux (and is available in a Snap port), so it might work in wine on MacOS, also. The only possible disadvantage is the large number of choices, but ...


1

There are options to produce a painted effect to an image in G'MIC (this can be either standalone or a GIMP plug-in). Both are free, gratis & open source, and available for Windows, OS-X, Linux and other platforms. Example of the G'MIC watercolour in action:


1

There is https://jspaint.app/ that is an online clone of Windows XP Paint. You probably can save the HTML page with JS and use it offline.


Only top voted, non community-wiki answers of a minimum length are eligible