ER diagram maker
Sketch a database in text: tables, their columns and how they relate. The ER diagram lays itself out, ready for a design review or the project docs.
How to use the ER diagram maker
- Start from the ER template, or paste your own code.
- Add a table with its columns inside { }, marking PK and FK.
- Link tables: CUSTOMER ||--o{ ORDER : places.
- Download a PNG, SVG, PDF or Word file.
What you get
- Tables with column types and keys
- One-to-one, one-to-many and many-to-many links
- Relationship labels
- Crow's foot notation
About the ER diagram maker
Reading the link symbols
|| means exactly one, o| zero or one, |{ one or more and o{ zero or more. CUSTOMER ||--o{ ORDER reads: one customer places zero or more orders.
From an existing database
Ask an AI assistant to turn your CREATE TABLE statements into a Mermaid erDiagram, then paste the answer here to check and export it.
Frequently asked questions
- How do I mark primary and foreign keys?
- Add PK or FK after the column name, for example int customer_id FK.
- Can a relationship label have spaces?
- Yes, in double quotes: PRODUCT ||--o{ LINE_ITEM : "appears in".
- Is my schema uploaded?
- No. It is drawn in your browser.