Jenner is a Web page templating system with a twist: it runs completely within a Web browser. Templates are just normal Web pages with special syntax inside text nodes, attributes, or comments. Unlike other in-browser templating systems, Jenner does not require overloading of "class" attributes or invalid HTML; all Jenner templates are valid Web pages and the template expressions flow in a very natural way. Having the template engine in the Web browser instead of on the server takes a lot of load off of the server, and makes for a clean separation of presentation and content. Jenner is very powerful: it has the full power of the Esel expression language at its disposal. Templates can be rendered from JSON data, and can be re-rendered without a browser-to-server round trip.
The KoreLogic Expression Language Library (libklel) is a C library that provides a simple expression language that can be embedded in other programs. It does not implement a full programming language, but rather a simpler expression language called KL-EL that is designed to provide arithmetic and logic operations in situations where embedding a full programming language would be overkill. KL-EL can access functions and variables exported from the embedding program, and is statically and strongly typed, which helps ensure that expressions are valid before they are executed. The embedding API is easy to use, and the library itself is very small.
Just out of curiosity, what editor is that in the screenshot?