Não esqueçam do mermaid que também da pra fazer diagramas muito bons...
sequenceDiagram
participant web as Web Browser
participant blog as Blog Service
participant account as Account Service
participant mail as Mail Service
participant db as Storage
Note over web,db: The user must be logged in to submit blog posts
web->>+account: Logs in using credentials
account->>db: Query stored accounts
db->>account: Respond with query result
alt Credentials not found
account->>web: Invalid credentials
else Credentials found
account->>-web: Successfully logged in
Note over web,db: When the user is authenticated, they can now submit new posts
web->>+blog: Submit new post
blog->>db: Store post data
par Notifications
blog--)mail: Send mail to blog subscribers
blog--)db: Store in-site notifications
and Response
blog-->>-web: Successfully posted
end
end