WPForms is the most popular free WordPress forms plugin by a large margin with over 4 million active installations. It’s feature set is constantly growing and it’s supported by a professional team of developers. At SaberWP we run WPForms on this site, using the free version as it has everything we currently need in a form plugin.
Gravity Forms is still widely listed as the #1 WP forms plugin. It’s been that way for a long-time. Having had some first-hand experience working with the GF codebase, I do wonder if there is anything that has a more modern approach to coding and could be a viable alternative. This is a dynamic ever-changing segment of the market. Every site needs some type of forms, and which plugin you choose can have a big impact on what you’ll be able to integrate with and what the quality of the user experience will be.
Caldera Forms is sadly no longer going to be with us at the end of 2021. They were often listed as one of the best featured free forms plugins. Though even the paid versions were often criticized for lacking the integrations and advanced features of major competitors, Caldera was appreciated for how much of it’s feature set was available for free to WordPress users.