Zovo ER Diagram

ER diagrams from your SQL tables.

Zovo ER Diagram turns SQL CREATE TABLE statements into an entity relationship diagram. Paste the DDL from PostgreSQL, MySQL or SQLite: each table becomes a box with all its columns and types, with PK, FK and UQ marks, and each foreign key becomes a line with crow's foot marks. The marks come only from the DDL: NOT NULL, primary keys and UNIQUE decide them, and the rules are written on the result. Tables that other tables reference are placed to the left. Lines run in the space between the tables, and a geometry check on the final drawing counts boxes that overlap and lines that cross a table, and reports both counts. The PDF is Letter, A4 or Tabloid. Large schemas go on to more pages with text of at least 7 pt, cut only between tables, with a page list of tables and relationships. You also get an SVG of the whole diagram, a CSV with one row per column and a JSON summary. A second tool checks the schema without drawing: foreign keys to missing tables or columns, type differences, tables without a primary key and duplicate names.

What it does

Reads CREATE TABLE from PostgreSQL, MySQL and SQLite DDL, including composite keys and quoted names
Other statements (indexes, views, ALTER, INSERT, triggers) are listed as skipped with their line numbers
Crow's foot marks taken only from NOT NULL, primary keys and UNIQUE, with the rules stated
Geometry check on the drawing: overlapping tables and lines that cross a table are counted
PDF (Letter, A4 or Tabloid) with text of at least 7 pt, SVG, CSV of columns and a JSON summary
A schema check: missing foreign key targets, type differences, tables without a primary key, duplicates

Try asking

“Draw an ER diagram for: CREATE TABLE users (id int PRIMARY KEY); CREATE TABLE orders (id int PRIMARY KEY, user_id int REFERENCES users(id));”

“Check this schema for broken foreign keys before I run the migration”

“Make a Tabloid PDF ER diagram of my MySQL dump”

Limitations

Up to 50 tables, 60 columns per table, 1,000 columns and 120 foreign keys in all, 200,000 characters of DDL
Reads CREATE TABLE only; ALTER TABLE ... FOREIGN KEY and other statements are listed as skipped, not drawn
A CREATE TABLE that does not parse in full is refused with the line number; it does not guess
It does not connect to a database or run the SQL
The PDF font covers Latin, Greek, Cyrillic and Vietnamese; Chinese, Japanese, Korean, Arabic, Hebrew and emoji show as ? in the PDF (the SVG, CSV and JSON keep them)
Files of large diagrams are kept for 1 hour so the download links work, then deleted; download the files to keep them

Add it

ChatGPT: once Zovo ER Diagram is approved, add it from the ChatGPT plugin directory.

Claude: go to Customize > Connectors > Add custom connector and enter https://er-diagram.zovo.one/mcp. No sign-in is needed. Once Zovo ER Diagram is listed in the Claude connector directory, you can add it from there too.

Other MCP clients can connect to the same endpoint: https://er-diagram.zovo.one/mcp