API Basics
★  Fundamentals
★  Error Codes
★  Examples
★  Batch Processing
★  Specification
★  SDKs
Data Tools
Telephony
Geolocation
Security and Networking
E-commerce
Imaging

SDKs - Software Development Kits

C# SDK
A C# class library (.dll) that can run on Windows, Silverlight and Windows Phone.

Go SDK
A Go language v1.4 client library package that is compatible with command line tools as well as the Goclipse IDE

Java SDK
An eclipse and maven based java library project, which can be used with JRE7

Node.js SDK
An Node.js npm package based on Node.js v0.12.4

PHP SDK
A PHP library based on PHP >= 5.3 and Composer dependency manager

Python SDK
A Python library based on Python 2.7, that uses PIP as the dependency manager

Ruby SDK
A Ruby Gem based on Ruby >= 2.0.0