Steem Developer Portal
ChainSync - https://github.com/aaroncox/chainsync
A simple library to stream blocks and operations for digesting into other mediums.
SteemIAPI - http://steem.esteem.ws/
Interactive Steem API swagger, open-source script allows you to interact with blockchain.
SteemSQL - http://www.steemsql.com/
A private Microsoft SQL server database with Steem blockchain data, subscription based, allows you to do flexible queries and analyze blockchain data.
eSync extracts Steem blockchain data and saves into Mongodb, written in Nodejs.
Many more projects and tools can be found at https://steemprojects.com