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 - https://github.com/eSteemApp/esync

eSync extracts Steem blockchain data and saves into Mongodb, written in Nodejs.

Many more projects and tools can be found at https://steemprojects.com