WPDASH - WPDASH is a multifunctional manager for unlimited WordPress sites.
POP (Prototyping on Paper) - POP helps you make interactive prototype with ease. If you can draw, you can design apps.
Google Sites - Access Google Sites with a free Google account (for personal use) or G Suite account (for business use).
Marvel - Turn sketches, mockups and designs into web, iPhone, iOS, Android and Apple Watch app prototypes.
Nextsale - Nextsale makes users feel the experience of shopping in a dynamic website.
Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.