Contact Form 7 is a popular, free, and easy-to-use form-creation tool for website administrators.
See Forms with WordPress: Contact Form 7.
Gravity Forms is a popular and easy-to-use form-generation tool.
See Forms with WordPress: Gravity Forms.
WP-Members is a popular, free tool to create a membership framework for your WordPress site that restricts content access to registered members only.
See Forms with WordPress: WP-Members.
Other WordPress form plug-ins or systems
If you are using a WordPress forms system not referenced above, you are encouraged to adapt one of the above-referenced methods. Most WordPress form plugins have an API, and typically one of the API hooks enables a developer to add functions once the form has completed the validation of a submission (this is what we are using for WP-Members and Gravity Forms).
- If you are running a fully custom form, take a look at the methods listed in Posting External Forms to Act-On.
- If you want to iframe an Act-On form or directly embed the source code for an Act-On form, take a look at Embedding Forms on a Website (Generic Options).
If you are looking to add your beacon tracking code to WordPress, this follows a different process.