mORMot is very well written and supported.
If you start with such code it is excellent. I use it myself on some of my own websites.
It is also well documented, although a bit complex/daunting for beginners.
Note all options given in this thread are proper options (with the exception of being able to handle wsdl, which is needed for the standard: webservices (ISO/IEC PAS 17963:2012 et al) are a standard) for interactive websites.
Just test all of them and make a choice what is comfortable to you. All of them contain good example code.
For inter-operability in commercial applications I would recommend using one of the solutions that fully supports those standards, though.