Formly - Collect data Anytime, Anywhere, even offline.
Siberian CMS - Siberian is an Open-Source and Free App Maker. Unlimited Push Notifications. Unlimited features. Fully Customizable. Download it and build your own app now!
FieldGoal - Don't build a whole backend just for one stupid form.
GoodBarber - GoodBarber is a mobile app creation platform.
Clearbit Forms - Data powered web forms designed for conversion
Bizness Apps - Create your own app or become a reseller and build apps for others