About ERDGenerator

ERDGenerator is a free, browser-based tool for turning database schemas into entity-relationship diagrams you can actually work with. Paste a CREATE TABLE script — PostgreSQL, MySQL, SQLite or SQL Server — a DBML file or a Prisma schema, or describe your application in plain English, and get a clean, editable diagram in seconds. There is no account to create and nothing to install: the editor runs in your browser, and the diagram is yours to rearrange, export and share.

Why we built it

Most databases outlive the diagrams that describe them. The schema keeps changing while the picture stays frozen — an outdated screenshot in a wiki, an exported PNG nobody re-exports, a hand-drawn file from three redesigns ago. A diagram is only useful as documentation if it is cheap to regenerate. When regenerating it costs an afternoon, it stops happening, and the next person on the project reads the migration files instead.

The existing modelling tools do not help much here. They are heavy desktop applications with steep learning curves and per-seat licences, built for designing a database from scratch — not for making sense of one that already exists. We wanted the opposite: paste SQL, see the diagram, drag things around, export what you need. Under a minute, no account, no download. The distance between your schema and its picture should be one paste.

What it does

  • SQL to diagram. A real SQL parser (not regex) reads your DDL — whether it is a tidy script or a raw dump — and rebuilds the full model: primary keys, nullability, defaults, unique constraints, inline and dump-style ALTER TABLE foreign keys, and many-to-many join tables all carry over to the diagram.
  • DBML and Prisma to diagram. Paste a DBML file or a schema.prisma and the same model is extracted, including @relation mappings. Useful when your team documents with DBML or your backend lives in Prisma.
  • English to schema. Describe your app — «a blog with users, posts, comments and tags» — and ERDGenerator proposes a normalized schema (3NF) with sensible keys, join tables and column types, which you then refine visually. It is a first draft to edit, not an oracle.
  • Visual editing. Add tables and columns, draw relationships with cardinalities (1:1, 1:N, N:M), auto-arrange the layout, undo with Ctrl+Z, and save named restore points when a design milestone is reached. Work autosaves as you go.
  • Export & share. Download PNG, SVG, or runnable DDL for PostgreSQL, MySQL, SQLite and SQL Server, plus DBML, a first-draft Prisma schema and portable JSON. Publish a read-only link so teammates and clients can explore the schema — revocable at any time.

How the parsing works

The import is not a pile of string matching. Each supported format has a real grammar: a tokenizer plus a parser that walks your DDL and builds a model of tables, columns and constraints before anything is drawn. That is what makes messy real-world input work — foreign keys declared in ALTER TABLE statements after the fact, quoted identifiers, comments, dialect-specific types. SQL, DBML and Prisma parsing all happen in your browser: your schema is not shipped to a server to be analyzed. The same internal model drives every export format, so what you see is what gets round-tripped.

Privacy: no accounts, no names

There is no sign-up, no email to give, no name to invent. Projects are tied to an anonymous browser cookie: your editor URL is tied to your browser, and nobody can guess their way into it. When you publish a share link, the recipient gets a read-only view of the diagram — they need no account either — and you can revoke that link whenever you want. The describe-your-app feature does send your description to a server so a schema can be proposed, so keep credentials and real customer data out of it; the SQL, DBML and Prisma imports never leave your browser.

Who it is for

Backend developers documenting a database they inherited or preparing a schema review. Students and job seekers modelling their first schemas — or explaining one in an interview. DBAs sketching a refactor before touching migration files. Technical writers who need an accurate diagram to sit next to an API reference. Product teams comparing a design before a migration. Freelancers who need to hand a clean, current diagram to a client at the end of a contract. If you think in tables and relations, this tool is for you.

What is next

The tool is young, and the roadmap follows what people actually do with it rather than a fixed master plan. Dialect coverage, layout quality on very large schemas and more export targets are the areas being worked on. We would rather ship fewer things that hold up than promise a list of features with dates attached.

Try it

The editor is free and requires no sign-up. Open the editor → If something is missing, broken, or awkward, tell us — feedback decides what gets built next.