JCS'94 is the first and only Jazz Jackrabbit level editor available today. We started making it after figuring out the tileset format earlier last year. The name was more or less copied from the editor of Jazz Jackrabbit2, but it has the release year of Jazz1 attached to it. The way you edit levels also is inspired quite a bit by the editor of Jazz Jackrabbit2.
Unlike the earlier versions the editor this release is very easy to get the hang of. Although this does not mean it doesn't have advanced features. Here's a short feature list.