Free and open-source data modeling tools
There are many free ways to draw an entity-relationship diagram, but they solve different problems. Some are quick diagram editors, some are database IDEs with a diagram view, and a few are full data modeling tools with logical and physical models, documentation and code generation. This guide groups the main options and explains what to look for.
Licenses and features change. This page reflects the projects as of November 2026; check each project's own site and license file before relying on it.
What to look for
- Open source or just free? An open-source license (MIT, Apache, GPL, AGPL) lets you self-host, audit and modify the tool, and protects you if the vendor changes course. "Free" plans of proprietary tools can have limits on diagrams, tables or features.
- Where your data goes. Hosted tools may store your schema on their servers. Browser-local and desktop tools keep it on your machine.
- Logical and physical modeling. Many diagram tools only draw tables. Data modeling tools also support business-level (logical) models, many-to-many relationships, reference data, and the step from logical to physical.
- Import and export. Can it read your existing SQL or database? Does it generate DDL for your platform, and formats like DBML, Mermaid or dbt?
- Documentation. Data dictionaries, PDF design documents and tables you can paste into a wiki.
- Version control. A readable file format lets you keep models in Git and review changes.
- Scale. Some editors slow down past a few hundred tables.
Browser-based data modeling and ERD tools
| Tool | License | Notes |
|---|---|---|
| EntityModel.com | Open source (MIT) | Conceptual, logical and physical models as tabs of one model; SQL import and DDL export for PostgreSQL, MySQL, Snowflake and Databricks; DBML, Mermaid, dbt, ODCS, JSON Schema, Avro; PDF design documents; reference data; models stay in your browser; CLI and MCP server for AI agents |
| ChartDB | Open source (AGPL-3.0) | Web diagram editor that imports a database schema through a single query; self-hostable |
| drawDB | Open source | Browser-based ERD editor with SQL export for several databases |
| dbdiagram.io | Proprietary, free tier | Diagrams written in DBML (a small text language); hosted |
| DrawSQL, SqlDBM | Proprietary | Hosted diagram and modeling services with free or trial tiers |
Diagrams as code
| Tool | License | Notes |
|---|---|---|
Mermaid erDiagram |
Open source (MIT) | Renders in GitHub, GitLab and many wikis; good for small diagrams in docs |
| PlantUML | Open source | Text-to-diagram, including entity-relationship diagrams |
| DBML | Open source language | The format behind dbdiagram.io; supported by other tools including EntityModel.com |
These are great for a README, but they're drawing languages rather than modeling tools: no validation, no reference data, no logical-to-physical step. EntityModel.com exports Mermaid and DBML, so you can model in a tool and publish as code.
Database IDEs with an ER diagram view
| Tool | License | Notes |
|---|---|---|
| DBeaver Community | Open source (Apache 2.0) | Universal database client; shows ER diagrams of an existing database |
| MySQL Workbench | Open source (GPL), Community edition | Visual modeling and forward/reverse engineering for MySQL |
| pgModeler | Open source (GPLv3) | PostgreSQL-specific modeler; source is free, prebuilt binaries are paid |
These are strongest when the database already exists and you want to see it, or when you target a single database engine.
Commercial data modeling suites
erwin Data Modeler, ER/Studio, Hackolade and SAP PowerDesigner are long-established enterprise tools with deep features (model repositories, governance integrations, many target platforms). They're paid, usually desktop software. If you need a lightweight, free alternative to them for logical and physical modeling and design documents, a browser-based modeler such as EntityModel.com covers the common workflow.
Side-by-side comparisons: EntityModel.com vs dbdiagram.io, vs erwin Data Modeler, vs Lucidchart.
How to choose
- A quick diagram of an existing database: a database IDE (DBeaver, MySQL Workbench) or a schema-import editor (ChartDB, EntityModel.com).
- A diagram in a README: Mermaid, or export Mermaid from a modeling tool.
- Designing a new model with business users: a tool with conceptual and logical models, descriptions, reference data and readable documentation. EntityModel.com is built for this.
- Data warehouse or lakehouse work (Snowflake, Databricks): check for DDL in those dialects, dbt output and schema import. EntityModel.com supports all three.
- Strict data privacy: browser-local or self-hosted open-source tools.
- Working with AI agents: a documented file format and an API or MCP server, so an agent can read and propose changes.
Frequently asked questions
What is the best free data modeling tool?
It depends on the job. For quick diagrams of an existing database, a database IDE such as DBeaver Community works well. For designing conceptual, logical and physical models with documentation and DDL for several databases, EntityModel.com is a free, MIT-licensed option that runs in the browser with no account.
Is there a free, open-source alternative to erwin Data Modeler?
EntityModel.com is a free, MIT-licensed, browser-based alternative for the core erwin workflow: logical and physical models, forward and reverse engineering, model comparison with migration SQL, naming standards, and design documents. It doesn't replicate every enterprise feature, such as a central model repository.
Is there an open-source alternative to dbdiagram.io?
Yes. EntityModel.com imports and exports DBML, so you can bring dbdiagram.io diagrams in, and it is open source under the MIT license. ChartDB and drawDB are other open-source diagram editors.
Can I make an ER diagram online without signing up?
Yes. EntityModel.com runs at entitymodel.com with no account; models are stored in your browser.