Contact Form 7 CiviCRM integration

Since I got this working (with some quick and helpful advice from the author) it has worked very well. I love the flexibility of the API/form processor approach, which basically lets you do anything API v3 can do. The functionality is better than the Caldera Forms it replaced and it's free! The catch is it's really quite difficult to set up because the documentation is incomplete and debugging is difficult (the "API REST Log" extension in CiviCRM looks useful but I couldn't get it to work). The two big "gotchas" that caught me were the example CiviCRM path was wrong for WordPress (should be wp-json/civicrm/v3/rest) and the names of the form fields must match the entity names in the API, some of which (custom fields) are quite hard to discover. The problem is, there are a lot of things you have to get right (paths, permissions, API keys, variable names, API and PHP versions) and there are so many permutations of all of these that if it doesn't work you can spend days and days googling for clues and tearing hair out.