We would be fine using existing frameworks and their form handling systems, but all of them feel very heavyweight. Either the backing objects need to be of some

We would be fine using existing frameworks and their form handling systems, but all of them feel very heavyweight. Either the backing objects need to be of some specific form, or the communication protocol between the server and the client is weird, or the generated markup is a mess. With Supler, we want to make it easy to customise the form, the form's markup and associated Javascript (to add any dynamic behaviour), so that you don't have to hack the framework, but instead so that you can use our library to generate the base and then customise further. One of the main points of Supler is that it takes care of both the frontend and the backend, so I don't think it would be possible to keep it entirely on the frontend. E.g. you define the form once, and you have partial validation on the frontend, and the same full validation on the backend (without having to repeat yourself).