About sql2erd

Last updated 3 September 2026

sql2erd turns SQL DDL into a clear entity relationship diagram. Paste CREATE TABLE statements, get a diagram with primary keys, foreign keys and orthogonal connectors — then export it as SVG or PNG.

Everything runs in your browser. There is no upload step, because there is nowhere to upload to.

How it works

Three stages, all client-side:

Parse — a Rust parser compiled to WebAssembly reads the DDL and builds a model of tables, columns and relationships, then emits a Graphviz DOT description.
Layout — Graphviz, itself compiled to WebAssembly, computes where each table should sit.
Render — the Rust module routes orthogonal connectors around the placed tables and writes the final SVG.

The status line under the editor reports how long each stage took, so the cost of a large schema is visible rather than guessed at.

Why static parsing

sql2erd never connects to a database. It reads the DDL text only. That is a deliberate trade-off: it means the tool works on a schema that has not been deployed yet, on a migration file in a pull request, or on a production dump you are not allowed to connect to — and it means your credentials are never involved. The cost is that anything not expressed in the DDL (data, statistics, runtime constraints) is invisible to it.

Dialects

PostgreSQL and MySQL DDL are supported, including table constraints, inline and separate FOREIGN KEY declarations, and ALTER TABLE … ADD CONSTRAINT. Layout can be centred on one table with concentric rings, which helps when a schema is large enough that a plain graph becomes unreadable.

There is also a command-line version

The same product exists as a local CLI that writes SVG and PNG files, useful for CI pipelines and for schemas you would rather not open in a browser at all. The two share a name and a design, but are separate implementations.

Privacy and terms

Nothing is collected — see the Privacy Policy, which explains how a Content-Security-Policy header enforces that rather than merely promising it. Usage is governed by the Terms of Use; note in particular that generated diagrams should be reviewed before you rely on them.

Contact

[email protected]