Mermaid syntax tutorial

Mermaid State Diagram Tutorial

State diagrams explain how an object, workflow, or UI moves between states. Use them when transitions and allowed events are the key information.

UI state machinesOrder and ticket lifecyclesProtocol states
Syntax

stateDiagram-v2

Examples

1 starter pattern

Review

5 production checks

Open Mermaid Editor

Diagram preview

Rendered Mermaid example

State Diagram
Mermaid State Diagram example

What You Will Learn

How to recognize when State Diagram is the right Mermaid diagram, write the opening declaration, and shape a readable first version.

Best Fit

UI state machines, Order and ticket lifecycles, Protocol states.

Start Here

Copy the starter example, replace labels with your domain language, then simplify anything that does not help the reader.

Syntax Basics

Start with the diagram declaration, then add the smallest set of labels, relationships, and annotations needed to communicate the idea.

  • Use stateDiagram-v2 for modern state diagrams.
  • Use [*] for start and end states.
  • Label transitions with events or conditions.
  • Nest states when a state has internal phases.

Official Documentation Coverage

The Mermaid documentation for State Diagram covers the following syntax areas. This tutorial condenses those topics into practical guidance for day-to-day documentation.

State declarations

State declarations is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Transitions

Transitions controls how elements connect. Treat these connections as the main information layer, and label them when direction, ownership, or meaning is not obvious.

Start and end markers

Start and end markers is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Composite states

Composite states is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Choice and fork nodes

Choice and fork nodes defines the named objects in the diagram. Keep names stable, domain-specific, and short enough to remain readable in exported images.

Notes

Notes is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Concurrency

Concurrency is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Diagram direction

Diagram direction is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

How This Tutorial Uses The Official Docs

Mermaid syntax evolves, so the official page remains the primary reference. This tutorial turns that reference material into an authoring workflow, review checklist, and production guidance.

Start with the official grammar

The official Mermaid State Diagram page is the source of truth for syntax changes. Use this tutorial to choose the right authoring pattern, then confirm exact keywords and edge cases in the official reference.

Prioritize the core sections

For the first pass, focus on State declarations, Transitions, Start and end markers, Composite states. These sections usually explain the minimum structure required for a valid State Diagram.

Add advanced syntax only when it earns its space

Treat Choice and fork nodes, Notes, Concurrency, Diagram direction as optional layers. They are valuable when the diagram needs precision, but they should not make the first version harder to read.

Syntax Reference Map

Use this map as a practical reading order for the official syntax page. It separates the first concepts to learn from the advanced details that are better added after the diagram already communicates the right idea.

Phase
How to use it
Start
State declarations

State declarations is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Does this state declarations detail make the state diagram easier to understand or maintain?

Start
Transitions

Transitions controls how elements connect. Treat these connections as the main information layer, and label them when direction, ownership, or meaning is not obvious.

Does this transitions detail make the state diagram easier to understand or maintain?

Refine
Start and end markers

Start and end markers is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Does this start and end markers detail make the state diagram easier to understand or maintain?

Refine
Composite states

Composite states is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Does this composite states detail make the state diagram easier to understand or maintain?

Refine
Choice and fork nodes

Choice and fork nodes defines the named objects in the diagram. Keep names stable, domain-specific, and short enough to remain readable in exported images.

Does this choice and fork nodes detail make the state diagram easier to understand or maintain?

Polish
Notes

Notes is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Does this notes detail make the state diagram easier to understand or maintain?

Polish
Concurrency

Concurrency is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Does this concurrency detail make the state diagram easier to understand or maintain?

Polish
Diagram direction

Diagram direction is part of the official Mermaid State Diagram syntax surface. Add it when the starter example needs more precision for production documentation.

Does this diagram direction detail make the state diagram easier to understand or maintain?

How To Study The Official Syntax

The official Mermaid page is broad because it documents the full parser surface. For a working tutorial, read it in passes instead of trying to memorize every option at once.

Step 1

Skim the official State Diagram documentation once to understand the full syntax surface before copying examples into production docs.

Step 2

Focus first on State declarations, Transitions, Start and end markers, Composite states, Choice and fork nodes because these topics usually explain the core authoring model.

Step 3

After the first diagram renders, revisit the official styling, configuration, and advanced sections only when the diagram needs that extra precision.

Authoring Workflow

This workflow turns the official syntax reference into a repeatable writing process for docs, specs, and product pages.

Step 1

Frame the reader question

Before writing syntax, decide what question the State Diagram should answer. Good diagrams usually answer one question clearly instead of answering several partially.

Step 2

Draft the smallest valid diagram

Start with the declaration for stateDiagram-v2, add only the required elements, and render it before introducing advanced styling or configuration.

Step 3

Add semantic labels

Replace placeholder names with business or system language that readers already know. Labels should reduce explanation work.

Step 4

Review for maintenance

Remove details that are likely to drift quickly. If a value, date, or dependency changes often, explain who owns the update.

Quick Syntax Cheat Sheet

Use this compact reference when you already know the goal and need to write a valid Mermaid State Diagram quickly.

Declaration
stateDiagram-v2

Start the code block with stateDiagram-v2 so Mermaid selects the State Diagram renderer.

Core content
Use stateDiagram-v2 for modern state diagrams.

Add the smallest number of statements that express the main idea before adding visual polish.

Connections
Label transitions with events or conditions.

Use connections only where they explain ownership, sequence, flow, dependency, or hierarchy.

Advanced topic
State declarations

Use official syntax topics as optional layers, not as requirements for every diagram.

Practice Prompts

Use these prompts after reading the official syntax sections. They force the diagram to stay practical instead of becoming a syntax inventory.

Exercise 1

Create a State Diagram for ui state machines using no more than eight visible elements.

Exercise 2

Rewrite the starter example with labels from your own product or engineering domain, then remove any line that does not change the reader's understanding.

Exercise 3

Add one official syntax feature from State declarations, Transitions, Start and end markers and explain why that feature makes the diagram clearer.

Exercise 4

Compare the result with flowchart and sequence-diagram and write one sentence explaining why State Diagram is still the better fit.

Examples

Copy the example into the Mermaid editor, then adjust labels and relationships for your own documentation.

Order Lifecycle

A simple lifecycle from draft to completion.

stateDiagram-v2
  [*] --> Draft
  Draft --> Submitted: submit
  Submitted --> Paid: payment received
  Submitted --> Cancelled: cancel
  Paid --> Shipped
  Shipped --> [*]

Example Walkthrough

Read Mermaid examples from top to bottom. The first meaningful line usually selects the diagram parser; the following lines add labels, relationships, values, states, or layout hints.

stateDiagram-v2

This line declares the Mermaid diagram type, which tells Mermaid which parser and renderer to use.

[*] --> Draft

This line adds a relationship, transition, message, data value, or visual item to the diagram.

Draft --> Submitted: submit

This line adds a relationship, transition, message, data value, or visual item to the diagram.

Submitted --> Paid: payment received

This line adds a relationship, transition, message, data value, or visual item to the diagram.

Submitted --> Cancelled: cancel

This line adds a relationship, transition, message, data value, or visual item to the diagram.

Paid --> Shipped

This line adds a relationship, transition, message, data value, or visual item to the diagram.

Shipped --> [*]

This line adds a relationship, transition, message, data value, or visual item to the diagram.

When To Use State Diagram

UI state machines
Order and ticket lifecycles
Protocol states
Workflow validation

Diagram Choice Guide

A strong Mermaid tutorial should also explain when not to use the diagram type. Use this guide before adding a State Diagram to a public page or technical design document.

Use this diagram when

State Diagram works best for ui state machines, order and ticket lifecycles, protocol states. It should make the reader's next decision easier, not merely decorate the page.

Choose a different diagram when

Your main question is better answered by another structure, such as flowchart, sequence-diagram, requirement-diagram. For example, use a sequence diagram for message order and a flowchart for branching process logic.

Keep it maintainable by

Keeping the first version small, naming every important element with business language, and linking back to the official Mermaid syntax page when advanced syntax is required.

Production Checklist

Before publishing a Mermaid State Diagram, run through this checklist so the diagram remains useful after the immediate conversation is over.

Confirm that State Diagram is the right diagram type for the problem.
Start from the smallest example that communicates the idea clearly.
Use consistent names for nodes, actors, states, or data labels.
Check the diagram in the Mermaid editor before publishing.
Add surrounding text that explains assumptions, scale, or business context.

Production Review Questions

Before shipping the diagram in public docs, compare it against the official syntax page and then ask whether each line helps the reader make a better decision.

Does the first line clearly select the Mermaid State Diagram renderer with stateDiagram-v2?
Are names and labels from the Choice and fork nodes area short, stable, and meaningful to the target reader?
Do the transitions details show real meaning instead of visual decoration?
Could a teammate update this diagram next month without rereading the whole surrounding document?

Troubleshooting

Most Mermaid issues come from an incorrect declaration, a syntax feature used before the base diagram works, or a diagram that is trying to communicate too many ideas at once.

The diagram does not render

Check that the first line is the correct declaration for State Diagram: stateDiagram-v2. Then remove advanced lines until the smallest version renders.

The diagram renders but is hard to read

Shorten labels, reduce the number of visible items, and split separate ideas into separate diagrams.

The meaning is ambiguous

Add edge labels, relationship names, axis labels, or surrounding explanatory text so readers know what the diagram is proving.

The diagram becomes stale

Prefer stable concepts over volatile implementation details, and add ownership notes when the diagram documents a changing system.

Publishing Notes

For SEO and long-term documentation quality, keep the Mermaid code close to the explanation. Search engines can understand the surrounding text, while engineers can copy the exact syntax into their own editor.

If the diagram is used in a product page, add a short caption that states what decision the diagram supports. If it is used in internal docs, add ownership and update expectations so the diagram does not become stale after the system changes.

Best Practices

  • -Name states as nouns or adjectives.
  • -Name transitions as events.
  • -Keep impossible transitions out of the diagram.
  • -Use nested states only when they simplify the model.

Common Mistakes

  • -Using actions as state names.
  • -Documenting every implementation flag as a state.
  • -Forgetting terminal states.

Choosing Related Diagram Types

If State Diagram does not quite match your communication goal, compare it with these nearby Mermaid diagram types.

Flowchart

Flowcharts turn decisions, processes, and branches into readable Mermaid diagrams. They are the best starting point when you need to document a workflow, product funnel, or engineering process.

Sequence Diagram

Sequence diagrams show how participants communicate over time. Use them when the order of messages matters more than the internal structure of each system.

Requirement Diagram

Requirement diagrams connect requirements, elements, and relationships such as satisfies, verifies, and derives. They help teams trace why a system feature exists.

FAQ

Is Mermaid State Diagram rendered on the server?

This tutorial page is server-rendered for SEO. The Mermaid syntax is shown as plain text so search engines and readers can inspect it without waiting for client-side rendering.

Can I edit this State Diagram example?

Yes. Open the Mermaid editor, paste the example, and modify the labels, relationships, or values for your own use case.