Markdown sequence diagram maker

Map out a sequence diagram online. Write the participants and messages as Mermaid text and see the interaction render live, ideal for API calls, auth flows and how services talk to each other.

Mermaid sequence syntax

A sequence diagram is a set of participants and the messages that pass between them, read top to bottom. You name the participants, then write one message per line. Here is each piece you can write.

Participants

List the participants first. Give each one a short id, and an optional label shown in the box.

You write

sequenceDiagram
  participant A as Alice
  participant B as Bob

You get

Messages

Draw a message from one participant to another with an arrow and a colon, then the text.

You write

sequenceDiagram
  participant A as Alice
  participant B as Bob
  A->>B: Are you free?
  B-->>A: Yes, at noon

You get

Arrow types

The arrow between the two ids sets the line style and the head.

You write

sequenceDiagram
  participant A
  participant B
  A->>B: Solid arrow
  A-->>B: Dashed arrow
  A->B: Solid line
  A-->B: Dashed line
  A-xB: Cross end
  A-)B: Open async

You get

Cheat sheet

Write this	You get
Participants
`participant A`	A participant named A
`participant A as Alice`	Id A shown as Alice
`actor A`	A participant drawn as a person
Messages
`A-->>B: Text`	Dashed arrow, filled head
`A->>B: Text`	Solid arrow, filled head
`A->B: Text`	Solid line
`A-->B: Text`	Dashed line
`A-xB: Text`	Line ending in a cross
`A-)B: Text`	Open async arrow