MIT App Inventor

• MIT App Inventor homepage
• MIT App Inventor Release Notes
• App Inventor 2
• App Inventor 2 Test Server
• App Inventor 2 Server without the 10 MB app limit
• Components Documentation
• Blocks Documentation
• Extensions Documentation
• Document: How to build App Inventor from the MIT sources
• Document: How to Add a Component
• App Inventor Source Files
• App Inventor discussion forum
• RGBA to App Inventor color calculator
• App Inventor color codes chart
• Comparison list by Peter

Thunkable

• Thunkable homepage
• Thunkable ✕ cross-platform development for iOS and Android
• Thunkable Community
• The blog from the Thunkable team
• Thunkable FAQ by Conor
• Thunkable Docs
• Thunkable Templates by Ben

Extension lists

• Extension Directory by Domhnall & others
• List of extensions by Taifun
• List of extensions by Sander
• List of Extensions by Conor & Thunkable Community

Open Source

• Emoji One
• Twemoji
• Open Source Extensions by Colin
• Material Design Icons
• Open Source Images
• Free icons database
• Open source css template
• Useful resources collected by Amoroso

Tutorials

• appinventor.org
• Bluetooth in App Inventor
• Pura Vida Tutorials
• Official App Inventor tutorials
• Other App Inventor tutorials
• The Evolution of Chat by Domhnall
• Various tutorials by Domhnall (link to his profile)
• Video tutorials (post)