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DDL to ER Diagram

Q: What counts as DDL?

Data Definition Language — the CREATE TABLE, ALTER TABLE and constraint statements that define your schema. Paste them and the diagram is drawn instantly.

Q: Does it read ALTER TABLE foreign keys?

Yes — foreign keys added via ALTER TABLE … ADD CONSTRAINT … FOREIGN KEY (as pg_dump emits) are parsed and drawn as relations.

Paste your database DDL — the CREATE TABLE and ALTER TABLE statements that define your schema — and get an interactive ER diagram with every table, column and foreign key drawn automatically.

Open the diagram tool →

No signup · nothing uploaded · export PNG / SVG / Mermaid / DBML · shareable link

ER diagram of the DDL to ER Diagram example schema: authors and books (2 tables, 1 relationship) — The DDL to ER Diagram example below, drawn by the tool: authors and books (2 tables, 1 relationship).

At a glance

What it is: SQL to ER Diagram is a free, open-source browser tool that turns SQL DDL into an interactive entity-relationship (ER) diagram.
Input: SQL DDL: CREATE TABLE and ALTER TABLE statements for PostgreSQL, MySQL, MariaDB, SQLite, SQL Server, Oracle or Snowflake.
Output: An interactive ER diagram you can rearrange, then export as PNG, SVG, Mermaid, DBML or PlantUML, or share as a link.
Cost: Free. MIT-licensed open source. No account or signup.
Privacy: Runs entirely in your browser. The schema is never uploaded, and share links carry the diagram in the URL fragment, which is not sent to a server.
Limits: It never connects to your database itself: you paste schema text, or run one read-only catalog query in your own client and paste the result. There are no accounts, so there is no real-time multi-user editing; diagrams are kept in your browser, as a saved file, or as a share link. Layout stays smooth at around 300 tables.

How it works

Copy your DDL from a migration, schema dump, or your database client.
Paste it into the editor — PostgreSQL, MySQL, SQLite, SQL Server, Oracle and Snowflake DDL all parse.
Tables render with columns; inline REFERENCES and FOREIGN KEY constraints become relations.
Arrange, hide tables, then export PNG/SVG or convert to Mermaid/DBML.

Example

DDL like this:

CREATE TABLE authors (
  id BIGINT PRIMARY KEY,
  name VARCHAR(120) NOT NULL
);

CREATE TABLE books (
  id BIGINT PRIMARY KEY,
  author_id BIGINT NOT NULL
);

ALTER TABLE books
  ADD CONSTRAINT fk_books_authors
  FOREIGN KEY (author_id) REFERENCES authors(id);

…renders two tables with a relation from books.author_id → authors.id, including the ALTER TABLE foreign key. Try it with your own →

Guide

DDL — CREATE TABLE, ALTER TABLE, ADD CONSTRAINT — is the most complete description of a schema that exists, and this page turns any dialect of it into a diagram. The reason this page exists separately from the per-database pages: real-world DDL is dialect soup. A migration folder might contain Postgres DDL; a vendor handover might include a SQL Server .sql script with GO batches; an ORM might emit SQLite-flavoured DDL. Paste any of them, or a mixture — the parser handles inline REFERENCES, named CONSTRAINT fk_… FOREIGN KEY blocks, and the ALTER TABLE-after-the-fact style that pg_dump produces.

Good sources of DDL you already have:

Your migrations folder — every framework's migrations are just DDL with extra steps.
pg_dump --schema-only, mysqldump --no-data, SSMS "Generate Scripts", sqlite3 .schema.
Terraform/Infrastrucure repos that manage databases declaratively.

Statements that don't affect the diagram — CREATE INDEX, GRANT, INSERT, CREATE VIEW — are skipped without complaint, so whole dump files paste fine.

Why use it

Private: everything runs in your browser — nothing is uploaded or stored on a server.
Dialect-agnostic — paste DDL from any major database.
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.
Free & open source — no account, no sign-up.

DDLPostgreSQLMySQLOracleSQL Server

FAQ

What counts as DDL?

Data Definition Language — the CREATE TABLE, ALTER TABLE and constraint statements that define your schema. Paste them and the diagram is drawn instantly.

Does it read ALTER TABLE foreign keys?

Yes — foreign keys added via ALTER TABLE … ADD CONSTRAINT … FOREIGN KEY (as pg_dump emits) are parsed and drawn as relations.

Is my schema uploaded anywhere?

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

Is it free?

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