Form processor with Contentful

I’m wondering what form processor people use along Contentful.

When I set up a site I always have at least one form to allow visitors to contact the website’s owner.

Some CMS systems have Form plugins. Sometimes forms point to 3rd party form processors or full blown Marketing automation systems.

I also saw stacks where the form was a Content Type or Channel with fields in the CMS, and visitors could submit into it via a public form.

Any ideas appreciated.