Best useful UNKNOWN links for Android Developers?

ANDROID DEVELOPERS UNKNOWN LINKS
(May be not for all but most of developers don't know about this)

1. Android Feature Graphic Generator
2. CodePath Android Cliffnotes
3. Talks by Chiu-Ki Chan
4. Android DP/PX Converter - Pixplicity
5. Android Experiments
6. DPI Calculator
7. The Central Repository Search Engine
8. Json Parser Online
9. jsonschema2pojo
10. Explore - Mashape - Free API Management Platform & Marketplace
11. Android Drawble Generator
12. we ♥ mobile and web
13. Android Niceties
14. Active Snippets - Android Snippets
15. Android Layout Finder | Buzzing Android
16. Gradle, please
17. Android Button Maker
18. AndroidKickstartR
19. Google Codelabs
20. Android Color Generator
21. The powerful Android Studio
22. strings.xml Generator

Thanks Happy coding.... :) Keep Sharing :)

Read Pratik Butani's answer to What are the best useful UNKNOWN links for Android Developers? on Quora