dbdiagram.io is a quick, simple & free ER diagram tool to help you draw your database diagrams using their own Domain-specific language (DSL).Top 10 Free Database Diagram (ERD) Design Tools To help you determine the right tool for you to design database schema diagrams, we've curated a list of 10 of the best free ERD tools to do it. And designing database schemas is one of the very first and important steps to start developing any software/website. A database schema is the blueprints of your database, it represents the description of a database structure, data types, and the constraints on the database.