Start learning Android https://developer.android.com
Create shadows for images Android 9-patch shadow generator fully customizable shadows http://inloop.github.io/shadow4android/
Easiest way to use svg in android- Android SVG to VectorDrawable one VectorDrawable to rule all screen densities http://inloop.github.io/svg2android/
JSON viewer http://jsonviewer.stack.hu/
Convert Json to data model(Pojo) class http://www.jsonschema2pojo.org/
Android Library database https://android-arsenal.com/
Android icons and images https://romannurik.github.io/AndroidAssetStudio/
Development/screencast android mobile - puts your Android on your desktop. https://www.vysor.io/
Sqlite browser viewer http://sqlitebrowser.org/
Sqlite alternative for android https://news.realm.io/news/realm-for-android/
Android Design inspiration https://material.uplabs.com/