Converter

Mermaid to PlantUML

Write or paste Mermaid, switch the format to PlantUML, and the converted text appears at once. Flowcharts become PlantUML activity diagrams. Anything that does not carry over is listed.

Convert Mermaid in the editor Free. No sign-up. Nothing is uploaded.

See it work

A Mermaid flowchart and the PlantUML activity diagram the editor produces from it:

flowchart TD
  A[Start] --> B{Valid?}
  B -->|yes| C[Process]
  B -->|no| D[Show error]
  C --> E([End])
  D --> E

@startuml
start
if (Valid?) then (yes)
  :Process;
else (no)
  :Show error;
endif
stop
@enduml

Sequence diagrams map one to one:

sequenceDiagram
  User->>App: open file
  App-->>User: preview

@startuml
User -> App : open file
App --> User : preview
@enduml

What converts

FlowchartSteps, decisions with yes/no branches, and loops, as an activity diagram.
SequenceParticipants, messages, notes, alt, loop and similar blocks.
Class, state, ERClasses with members and relations, states with transitions, entities with attributes.
Gantt, mind mapSections with tasks, and nested mind map branches.

Styling such as classDef colors, themes and link styles has no PlantUML counterpart here. Lines like that are listed in the loss report instead of being dropped silently.

Private by design

Rendering and converting both run inside your browser. The page is not allowed to open connections to other servers, so your diagram text is not uploaded. Your work is kept in your browser's local storage only. Details are in the privacy policy.

Questions

Why does my flowchart look different after converting?

PlantUML activity diagrams are structured (if, while, repeat). The editor rebuilds that structure from your graph. The meaning stays the same, the layout is decided again by PlantUML.

Can I convert back?

Yes. Switching straight back restores your original Mermaid text exactly.

Is the result guaranteed to be complete?

Converted results are provided as is. Check the preview and the list of what was not carried over before you rely on them.