Simple html tag

You can use Gravizo including an image tag <img src='http://g.gravizo.com/g? follow by a graph description writed in DOT, PlantUML or UMLGraph, and then close the image tag

<img src='http://g.gravizo.com/g?
 digraph G {
   main -> parse -> execute;
   main -> init;
   main -> cleanup;
   execute -> make_string;
   execute -> printf
   init -> make_string;
   main -> printf;
   execute -> compare;
 }
'/>

Using markdown syntax in github.com

Also can use Markdown syntax including a image tag and then the url content include DOT, PlantUML or UMLGraph syntax. Don't forget to close the image tag.

![Alt text](http://g.gravizo.com/g?
  digraph G {
    aize ="4,4";
    main [shape=box];
    main -> parse [weight=8];
    parse -> execute;
    main -> init [style=dotted];
    main -> cleanup;
    execute -> { make_string; printf}
    init -> make_string;
    edge [color=red];
    main -> printf [style=bold,label="100 times"];
    make_string [label="make a string"];
    node [shape=box,style=filled,color=".7 .3 1.0"];
    execute -> compare;
  }
)

Use it on you README.md at github to show the graph directly in your home page. Here is a sample

<img src='http://g.gravizo.com/g?
@startuml;

actor User;
participant "First Class" as A;
participant "Second Class" as B;
participant "Last Class" as C;

User -> A: DoWork;
activate A;

A -> B: Create Request;
activate B;

B -> C: DoWork;
activate C;

C --> B: WorkDone;
destroy C;

B --> A: Request Created;
deactivate B;

A --> User: Done;
deactivate A;

@enduml
'>
        
<img src='http://g.gravizo.com/g?
/**
*Structural Things
*@opt commentname
*@note Notes can
*be extended to
*span multiple lines
*/
class Structural{}

/**
*@opt all
*@note Class
*/
class Counter extends Structural {
        static public int counter;
        public int getCounter%28%29;
}

/**
*@opt shape activeclass
*@opt all
*@note Active Class
*/
class RunningCounter extends Counter{}
'>