Free ERD Diagram Tool — Map Tables and Links

See it work

ERD diagram tool examples.

Same tool, four requests. Every drawing below is a real render.

What you type

Create a multi-tenant SaaS RBAC ERD with Tenant, User, Membership, Role, Permission, RolePermission, Invitation, and AuditEvent tables, the shown keys and attributes, memberships joining tenants and users, roles and permissions, and tenant audit events.

Then tryAdd API keys.Add role inheritance.

Entity-Relationship Diagram (ERD): SaaS access control

Entity-Relationship Diagram (ERD) · Chen 1976 / Everest 1976 (crow's foot) · schematex-erd

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The drawing

What an ERD diagram tool does.

An ERD diagram tool makes a database structure visible. It draws the tables, attributes, keys, and relationships that are easy to lose in a written requirements document or a list of SQL tables.

Use it to test a model before implementation: look for missing links, duplicate concepts, and many-to-many relationships that need a join table. The diagram then becomes useful documentation for developers and analysts.

Standard: Chen 1976 / Everest 1976 (crow's foot)
Also follows: Implements the crow's-foot subset
Engine: schematex-erd
Editable: Double-click text, drag nodes
Export: SVG · PNG · PDF

Entity-Relationship Diagram (ERD): What an ERD diagram tool does

Who uses it

Who uses an ERD diagram tool.

Healthcare software teams

Tenant, patient, provider, appointment, and CRM records mapped for a multi-organization application.

Security teams

Assets, vulnerabilities, patches, and remediation records connected for a vulnerability-management database.

IT operations teams

Assets, locations, maintenance tasks, and technicians organized for lifecycle tracking.

How it works

How to make an ERD diagram in three steps.

Describe it

One paragraph is enough to start.

“Create a multi-tenant SaaS RBAC ERD with Tenant, User, Membership, Role, Permission, RolePermission, Invitation, and AuditEvent tables, the shown keys and attributes, memberships joining tenants and users, roles and permissions, and tenant audit events.”

See the drawing

Drawn by the right engine.

Say what changes

Every edit keeps a version.

Add API keys.

V2 · DRAWN FROM V1, NOTHING RETYPED

FAQ

Common questions

What is an ERD diagram tool?

An ERD diagram tool creates a visual model of database entities, their fields, and their relationships. It helps a team see the data structure behind an application or process.

What are primary and foreign keys in an ERD?

A primary key uniquely identifies a row in its table. A foreign key stores the primary-key value from another table, creating a relationship between the two tables.

When do I need a join table?

Use a join table for a many-to-many relationship. For example, a Membership table can connect users and roles, or an OrderLine table can connect orders and products.

Can an ERD help document an existing database?

Yes. Describe the known tables, fields, and foreign-key relationships to create a readable overview for onboarding, reviews, or planning a change.

How do I start an ERD?

Start with the important records the system keeps, then state which record belongs to which. Add the identifier and the fields needed for the business rule you are modeling.

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