Free Online Database Diagram Tool: Visualize Your Schema in Seconds

The short version

You need a database diagram. You don't want to pay for it, sign up for another account, or install anything. A free online database diagram tool should let you paste SQL or connect to your database and get a visual schema in seconds.

Most tools claim to be free, then hit you with table limits, export restrictions, or require an email before you can do anything. The one that actually works the way you expect is dbdiagramr -- paste SQL or a PostgreSQL connection string, get an interactive ER diagram, export SVG/PNG. No signup, no limits, no catch.

What a good free database diagram tool should do

How to use dbdiagramr as your free database diagram tool

Option 1: Paste SQL

If you have a SQL dump or migration file, paste it directly into dbdiagramr and see your ER diagram appear instantly. Works with PostgreSQL CREATE TABLE statements, foreign keys, indexes -- the whole schema.

Option 2: Connect to a live database

If you have a PostgreSQL connection string, paste it into dbdiagramr. It queries information_schema for tables, columns, primary keys, and foreign keys, then renders an interactive ER diagram you can pan, zoom, drag, and export as SVG or PNG. Your SQL never leaves your browser -- the connection happens client-side.

Option 3: Upload a file

Drag and drop a .sql file or use the file picker. Same result -- instant diagram.

Why most "free" database diagram tools aren't actually free

dbdiagramr has none of these limits. Paste SQL, connect to your database, export as much as you want. The tool is open-source -- you can even self-host it.

Real example: visualizing a Supabase schema

Supabase projects come with auth, storage, and realtime tables out of the box. Understanding how they connect requires a diagram.

Paste this SQL into dbdiagramr:

CREATE TABLE users (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  email TEXT UNIQUE NOT NULL,
  created_at TIMESTAMPTZ DEFAULT NOW()
);

CREATE TABLE posts (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id UUID REFERENCES users(id) ON DELETE CASCADE,
  title TEXT NOT NULL,
  content TEXT,
  published BOOLEAN DEFAULT FALSE,
  created_at TIMESTAMPTZ DEFAULT NOW()
);

CREATE TABLE comments (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  post_id UUID REFERENCES posts(id) ON DELETE CASCADE,
  user_id UUID REFERENCES users(id) ON DELETE CASCADE,
  body TEXT NOT NULL,
  created_at TIMESTAMPTZ DEFAULT NOW()
);

In two seconds you see: users -- posts -- comments with all foreign key relationships drawn. Drag the boxes around, zoom in, export as PNG for your README.

When to use a free tool vs. a paid one

Use a free tool when:

• You're exploring an existing schema
• You need a quick diagram for documentation
• You're a solo developer or small team
• You want to understand relationships before writing queries

Consider paid when:

• You need real-time collaboration (Lucidchart, DrawSQL paid)
• You need version control integration (some enterprise tools)
• You're designing a schema from scratch with a large team

For 90% of database diagramming tasks, a free tool is enough.

FAQ

What's the best free online database diagram tool?
dbdiagramr is the best free option -- no table limits, no signup, open-source. Paste SQL or connect to a live PostgreSQL database.

Can I create a database diagram without signing up?
Yes. dbdiagramr requires no account. Go to the site, paste SQL, get your diagram.

Does it work with PostgreSQL only?
Currently yes. PostgreSQL is the most common target for ER diagrams, and dbdiagramr specializes in it. SQL paste works with any PostgreSQL-compatible syntax.

Can I export the diagram?
Yes. Export as SVG or PNG with one click. No paid plan required.

Is my database connection secure?
Yes. dbdiagramr connects to your database client-side. Your connection string never leaves your browser. No data is sent to any server.