Oracle to ER Diagram

How it works

1. Export the schema DDL — in SQL Developer (right-click the schema → Export), or via DBMS_METADATA.GET_DDL.
2. Paste it into the editor — the Oracle SQL is parsed automatically.
3. Tables render with columns and types; CONSTRAINT … FOREIGN KEY relations are drawn.
4. Arrange, hide tables, then export PNG/SVG or convert to Mermaid/DBML.

Example

An Oracle schema like this:

CREATE TABLE customers (
  id NUMBER GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
  email VARCHAR2(255) NOT NULL UNIQUE
);

CREATE TABLE orders (
  id NUMBER GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
  customer_id NUMBER NOT NULL,
  CONSTRAINT fk_orders_customers
    FOREIGN KEY (customer_id) REFERENCES customers(id)
);

…renders two tables with a relation from orders.customer_id → customers.id. Try it with your own →

Guide

Oracle schemas reach you in a few dialects of DDL and all of them parse here. The two common sources: SQL Developer's export (right-click the schema → Export, format SQL, data = no), and SELECT DBMS_METADATA.GET_DDL('TABLE', t.table_name) FROM user_tables t; which prints CREATE TABLE statements directly. Paste either, including the ALTER TABLE … ADD CONSTRAINT blocks that follow.

Oracle-isms that are handled

• NUMBER(38,0), VARCHAR2, RAW, CLOB/BLOB, and TIMESTAMP(6) WITH TIME ZONE.
• Identity columns: GENERATED BY DEFAULT AS IDENTITY (12c+) and legacy SEQUENCE-based keys.
• Double-quoted identifiers, TABLESPACE/STORAGE clauses, and PCTFREE noise — parsed or skipped cleanly.

A practical tip for big ERP-style schemas: export only the modules you're diagramming. Oracle instances routinely have thousands of tables across owners; a focused paste of, say, the AP and AR tables gives a diagram a finance team can actually read. And since nothing is uploaded, it's safe for schemas whose table names are sensitive.

Why use it

• Private: everything runs in your browser — nothing is uploaded or stored on a server.
• Interactive: drag tables, auto-arrange, hide noise, add notes, and manually link columns.
• Export a high-res PNG, vector SVG, or the schema as Mermaid / DBML / PlantUML code.
• Handles Oracle types like NUMBER / VARCHAR2 and named constraints.
• Free & open source — no account, no sign-up.

FAQ

How do I create an ER diagram from an Oracle database?

Export the schema DDL with SQL Developer or DBMS_METADATA.GET_DDL, then paste the CREATE TABLE statements here. Foreign-key constraints become relations automatically.

Is my schema uploaded anywhere?

No. Everything runs locally in your browser — your schema is never uploaded to or stored on any server.

Can I export the diagram?

Yes — export a high-resolution PNG or vector SVG, copy the schema as Mermaid, DBML or PlantUML, or share a link that encodes the whole diagram in the URL.

Is it free?

Yes. It is completely free and open source, with no account or sign-up required.

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