Lisp is great for creating your own domain specific languages. S-expressions are basically abstract syntax trees written as code. Thus you can take any code written in any language and "lispify" it into an S-expression. Then you can apply various transformations/analyses on this expression to achieve various goals:linting, semantic modeling, compiling to machine code/bytecode, transpiling to another laguage, interpreting, optimizing, etc. Common Lisp also has the possibility of on-the-fly recompilation of classes and methods/functions which can be useful for debug and incremental development.I don't have much experience in the web development area but I would incline to think that you won't get much added value from using CL compared to other languages/frameworks. It can be useful if you want to develop your own framework with custom language constructs and features. But if you want to fast prototype a webapp idea you're better off trying the more popular solutions.