Peetch - The last PowerPoint Pitchdeck you’ll ever need
Unleash - Open source Feature toggle/flag service. Helps developers decrease their time-to-market and to increase learning through experimentation.
Marvel for iOS - Rapid design and prototyping for the iPhone and iPad
Keynotopia - Prototyping straight into Keynote or Powerpoint
Google Sites - Access Google Sites with a free Google account (for personal use) or G Suite account (for business use).
Mobile Mockup Maker - The simplest way to create a beautiful mobile mockup