DGMO vs Mermaid vs PlantUML vs D2

Choosing the right text-to-diagram tool. Compare syntax, rendering quality, and features side by side.

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Feature comparison

How the four tools stack up across key capabilities.

Feature DGMO Mermaid D2 PlantUML
Sequence diagrams ✓ ✓ ✓ ✓
Flowcharts ✓ ✓ ✓ ✓
Data charts (bar, line, pie...) 15+ types 4 types — —
Interactive / clickable output ✓ — — —
No boilerplate / wrappers ✓ — — —
CLI tool ✓ ✓ ✓ ✓
Obsidian plugin ✓ Built-in — ✓
MCP / AI integration ✓ — — —
GitHub native rendering — ✓ — —
Dark theme built-in ✓ Config — —
Price Free / $29 app Free Free Free

Sequence diagram

The same login flow in all four languages. Source on the left, rendered output on the right.

DGMO 6 lines 
chart: sequence

Browser -POST /login-> Server
Server -SELECT user-> Database
Database -user record-> Server
Server -200 OK + token-> Browser
BrowserServerDatabasePOST /loginSELECT useruser record200 OK + token
Mermaid 8 lines 
sequenceDiagram
    participant Browser
    participant Server
    participant Database
    Browser->>Server: POST /login
    Server->>Database: SELECT user
    Database-->>Server: user record
    Server-->>Browser: 200 OK + token
DatabaseServerBrowserDatabaseServerBrowserPOST /loginSELECT useruser record200 OK + token
D2 6 lines 
shape: sequence_diagram

Browser -> Server: POST /login
Server -> Database: SELECT user
Database -> Server: user record
Server -> Browser: 200 OK + token
BrowserServerDatabase POST /loginSELECT useruser record200 OK + token
PlantUML 6 lines 
@startuml
Browser -> Server: POST /login
Server -> Database: SELECT user
Database --> Server: user record
Server --> Browser: 200 OK + token
@enduml
BrowserServerDatabaseBrowserBrowserServerServerDatabaseDatabasePOST /loginSELECT useruser record200 OK + token

Flowchart

A decision flow. DGMO infers shapes from brackets — no manual declarations needed.

DGMO 6 lines 
chart: flowchart

[Request] -> <Authenticated?>
  -yes-> [Load Dashboard]
  -no-> /Show Login/
/Show Login/ -> [Enter Credentials] -> <Authenticated?>
yesnoRequestAuthenticated?Load DashboardShow LoginEnter Credentials
Mermaid 6 lines 
flowchart TD
    A[Request] --> B{Authenticated?}
    B -->|Yes| C[Load Dashboard]
    B -->|No| D[Show Login]
    D --> E[Enter Credentials]
    E --> B

Yes

No

Request

Authenticated?

Load Dashboard

Show Login

Enter Credentials
D2 7 lines 
Request -> Authenticated?
Authenticated? -> Load Dashboard: Yes
Authenticated? -> Show Login: No
Show Login -> Enter Credentials
Enter Credentials -> Authenticated?

Authenticated?.shape: diamond
RequestAuthenticated?Load DashboardShow LoginEnter Credentials YesNo
PlantUML 12 lines 
@startuml
start
:Request;
if (Authenticated?) then (Yes)
  :Load Dashboard;
else (No)
  :Show Login;
  :Enter Credentials;
  :Retry;
endif
stop
@enduml
RequestAuthenticated?YesNoLoad DashboardShow LoginEnter CredentialsRetry

Class diagram

An abstract shape hierarchy. DGMO uses natural keywords — extends, [abstract] — instead of arrows.

DGMO 14 lines 
chart: class

Shape [abstract]
  +area(): number

Circle
  -radius: number

Rectangle
  -width: number
  -height: number

Circle extends Shape
Rectangle extends Shape
«abstract»Shape+ area(): numberCircle- radius: numberRectangle- width: number- height: number
Mermaid 14 lines 
classDiagram
    class Shape {
        <<abstract>>
        +area() number
    }
    class Circle {
        -radius: number
    }
    class Rectangle {
        -width: number
        -height: number
    }
    Circle --|> Shape
    Rectangle --|> Shape

Shape

<<abstract>>

+area() : number

Circle

-radius: number

Rectangle

-width: number

-height: number
D2 18 lines 
MyShape: {
  shape: class
  +area(): number
}

MyCircle: {
  shape: class
  -radius: number
}

MyRectangle: {
  shape: class
  -width: number
  -height: number
}

MyCircle -> MyShape: extends
MyRectangle -> MyShape: extends
MyShape+area()numberMyCircle-radiusnumberMyRectangle-widthnumber-heightnumber extendsextends
PlantUML 17 lines 
@startuml
abstract class Shape {
    +area(): number
}

class Circle {
    -radius: number
}

class Rectangle {
    -width: number
    -height: number
}

Circle --|> Shape
Rectangle --|> Shape
@enduml
Shapearea(): numberCircleradius: numberRectanglewidth: numberheight: number

When to use what

Honest recommendations. Every tool has its strengths.

DGMO

Concise syntax, beautiful rendering, interactive presentations, data charts

If you want the least boilerplate, dark-themed output, and a single language for both diagrams and data charts, DGMO is built for that.

Mermaid

GitHub/GitLab native rendering, maximum community support

If your diagrams live in GitHub READMEs or you need the largest ecosystem of integrations, Mermaid is the established choice.

D2

Container and architecture diagrams with auto-layout

D2 excels at nested container layouts and has a polished Go CLI. Great for infrastructure and architecture diagrams.

PlantUML

Existing team usage, deep IDE integrations, UML-strict diagrams

PlantUML has decades of history and integrations. If your team already uses it, switching may not be worth it.

Frequently asked questions

What is the difference between DGMO and Mermaid?

DGMO uses a more concise syntax with less boilerplate, supports 15+ data chart types (bar, line, pie, scatter, etc.) that Mermaid lacks, and produces interactive SVG output with click-to-source navigation. Mermaid has broader ecosystem support including native rendering in GitHub and GitLab.

Is DGMO free?

The CLI, npm library, playground, and MCP server are all free and open-source. The desktop app (Diagrammo) has a 14-day free trial, then costs $14.99/year.

Can I use DGMO in GitHub READMEs?

Not natively — GitHub only renders Mermaid diagrams inline. You can use the dgmo CLI in CI to render diagrams to SVG or PNG and embed the images in your README.

Does DGMO support dark mode?

Yes. DGMO has built-in dark and light themes, plus 8 color palettes (Nord, Catppuccin, Solarized, Gruvbox, Tokyo Night, Rose Pine, One Dark, and Bold).

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