Modelly

A browser-based data modelling tool for designing entity-relationship models.

Modelly helps data architects, analysts and engineers design, document and share data models. Build conceptual and logical entity-relationship (ER) diagrams directly in the browser — no installation — and keep the model, its documentation and its diagrams together in one place.

Features

• Entity-relationship diagrams — entities, attributes, data types, primary and foreign keys, crow's-foot cardinality and optionality, and identifying and non-identifying relationships.
• Automatic key migration — foreign keys propagate through relationships, including chains of identifying relationships, and stay in step when keys change.
• Subject-area domains — group entities into domains, each with its own colour, owner and description, with an on-diagram key.
• Multiple diagrams per model — present different views of the same model, and show or hide entities on a diagram without losing their layout.
• Documentation on the canvas — definitions for every entity and attribute, entity notes, free text notes, and a title block with author, version, date and status.
• Auto layout — tidies your own arrangement by aligning boxes, evening out spacing and re-routing relationship lines, without reshuffling the diagram.
• Model warnings — highlights modelling problems as you work.
• Export — PNG, JPG and SVG images, DBML for database tooling, and the complete model as a JSON file.
• Team editing — models are stored centrally. One person edits a model at a time by checking it out, while everyone else follows along read-only as changes are saved.

Who it's for

Data architects, data modellers, business analysts and software engineers who need to agree on the structure of their data — for new database designs, data warehouse and reporting models, integration work, or documenting existing systems.

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