Templates

Starters for engineers, product, and security—sequence diagrams, flowcharts, state, and class models.

Start faster with ready-made Mermaid diagram templates. Browse sequence diagram templates, flowcharts, state machines, and class diagrams — then open any template in the editor.

Basics

Basic sequence

Example

Two participants with a request and reply.

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Request–reply sketch

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Numbering

Autonumber

Example

Numbered steps for ordered messages.

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Ordered messaging

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Branching

Alt / Else

Example

Branch on success or failure.

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Success and error paths

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Loops

Loop

Example

Iterate until a condition is met.

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Repeated polling or heartbeat

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Optional blocks

Opt

Example

Optional fragment when something may happen.

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Optional step or side effect

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Activation

Example

Show active focus when a call is in progress.

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Call stack / focus on a lifeline

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API & backends

REST + database

Example

For backend devs documenting CRUD-style reads.

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HTTP API hitting a database

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Auth & identity

OAuth-style sign-in

Example

Simplified OAuth-style sign-in for app security discussions.

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Authorization flow with an identity provider

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Events & async

Async events / queue

Example

For integration and event-driven architectures.

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Publish, deliver, consume

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Flowcharts

Flowchart decision

Example

For PMs and ops mapping approvals.

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Approvals and branching

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State machines

State lifecycle

Example

For support and delivery workflows.

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Ticket or task lifecycle

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Class models

Class diagram

Example

For architects sketching a small domain model.

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Orders and line items (domain sketch)

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