ASO Tools

AppAnnie - https://www.appannie.com/

Sensortower - https://sensortower.com/

Apptweak - https://www.apptweak.com/

Appnique - http://appnique.com/

Appmind - http://appmind.co/

Buy graphics for games:

Graphicriver - http://graphicriver.net/

Photoeditoronlinefree - http://www.photoeditoronlinefree.com/

Gimp - http://www.gimp.org/

Inkscape - https://inkscape.org/en/

Paint.NET - http://www.getpaint.net/index.html

Buy music for games:

Looperman - http://www.looperman.com/

Partnersinrhyme - http://www.partnersinrhyme.com/pir/free_music_loops.shtml

Freesound - http://www.freesound.org/

Audiojungle - http://audiojungle.net/

Freemusicarchive - http://freemusicarchive.org/

App UI Designs:

Pttrns - http://pttrns.com/

Mobile-patterns - http://www.mobile-patterns.com/

Inspired - http://inspired-ui.com/

Mobilemozaic - http://www.mobilemozaic.com/

Lovelyui - http://www.lovelyui.com/

App localization 

Icanlocalize - http://www.icanlocalize.com/site/

Onehourtranslation - https://www.onehourtranslation.com/

Localizedirect - https://localizedirect.com/storefront/

Locteam - http://www.locteam.com/

Oneskyapp - http://www.oneskyapp.com/

Note : we will update this page with  useful resources regularly.