As of 29 mar 2016, there is a dev version of webform, but they're not confident in it enough even to publish it as dev: https://www.drupal.org/node/7404/release?api_version%5B%5D=7234
There's also eform, which is a D8 version of the entityform module: https://www.drupal.org/project/eform
When you're digging through dev versions, a good metric is looking at how many people are using that version-- check the per-version usage stats. Ideally you want thousands or tens of thousands of sites reporting, but we're not there yet.
For now, I'm hacking the d8's core contact module. I hope that a more complete solution will be available soon.
People who say you shouldn't use dev modules on production sites are living in the past. Drupal 7 would have been functionally unusable to a huge chunk of its user base for a long time if no one put dev modules into production. There are still dev modules that are integral to the function of thousands of substantial d7 sites. Drupal 8 is nothing but a toy without relying on dev modules-- the form question being an excellent illustration.