vs
Mermaid Chart vs PlantUML
The two main diagram-as-code options. Mermaid Chart is the hosted editor for Mermaid, the syntax GitHub renders natively, with AI and a 3-diagram free plan; PlantUML is free, open source and runs offline, strongest for UML.
Which one to pick
Pick Mermaid Chart if
CodeWords
- Your diagrams live in GitHub, GitLab or a wiki that renders Mermaid
- You want a visual editor and AI on top of the code
- You want AI to write and fix the Mermaid for you
Pick PlantUML if
Code
- You want it free with no limits, running on your own machine
- You draw a lot of UML: sequence, class, component, deployment
- Your build should render diagrams with no outside service
Where they differ most
Ways to draw
- Mermaid Chart
- Code, Words
- PlantUML
- Code
Free for work use
- Mermaid Chart
- Not statedNot stated
- PlantUML
- YesYes
Cheapest paid plan
- Mermaid Chart
- $10/month, Plus (billed yearly)
- PlantUML
- Free
Free version
- Mermaid Chart
- Free plan
- PlantUML
- Free and open source
AI from a text prompt
- Mermaid Chart
- YesYes
- PlantUML
- NoNo
Diagram code
- Mermaid Chart
- Mermaid
- PlantUML
- PlantUML, Graphviz
Every fact, side by side
Highlighted rows differ. Rows with an info mark open a note.
Mermaid ChartPlantUMLHow you make a diagram
Ways to draw (differs)Code, WordsCode
Free plan and prices
Cheapest paid plan (differs)$10/month, Plus (billed yearly)Free
What you get out
PNG YesYesYesYes
Where it runs and where files live
Apps (differs)WebWeb, Windows, Mac, Linux
