Mermaid Diagram Editor
Create flowcharts, sequence diagrams, class diagrams, and more with our free online Mermaid diagram editor. Features live preview, multiple diagram types, and easy export options.
Create professional diagrams using Mermaid syntax with real-time preview. Perfect for software documentation, system design, and process visualization.
Features
Real-time Diagram Preview
Instantly visualize your Mermaid diagrams as you type with live preview
Multiple Diagram Types
Support for flowcharts, sequence diagrams, class diagrams, and more
Export & Share
Export diagrams as SVG or PNG, and share your work with others
Frequently Asked Questions
What is Mermaid diagram syntax?
Mermaid is a simple markdown-like syntax for creating diagrams. It allows you to create various types of diagrams including flowcharts, sequence diagrams, class diagrams, and more using text-based descriptions.
What types of diagrams can I create with Mermaid?
You can create flowcharts, sequence diagrams, class diagrams, entity relationship diagrams (ERD), state diagrams, Gantt charts, pie charts, and user journey diagrams using Mermaid syntax.
How do I export my Mermaid diagrams?
You can export your diagrams as SVG or PNG files using the export button in the toolbar. You can also share your diagrams with others using the share button, which generates a unique URL containing your diagram code.
Can I use Mermaid diagrams in my documentation?
Yes! Mermaid diagrams are widely supported in documentation tools like GitHub, GitLab, and various Markdown processors. You can copy the diagram code and use it directly in your documentation.
Where can I learn more about Mermaid?
Explore these official resources and learning materials:
Official Documentation:
- Mermaid Documentation - Complete Mermaid guide
- Mermaid Syntax - Diagram syntax reference
- Mermaid Live Editor - Official online editor
- Mermaid GitHub - Source code and examples
Diagram Types:
- Flowcharts - Decision flows and processes
- Sequence Diagrams - System interactions
- Gantt Charts - Project timelines
- Class Diagrams - Object-oriented design
Integration & Tools:
- GitHub Integration - Native GitHub support
- VS Code Extension - Editor integration
- Mermaid CLI - Command line tools
These resources cover everything from basic diagrams to advanced integrations!
Mermaid Syntax Guide
Quick reference for creating flowcharts, sequence diagrams, class diagrams, and more with Mermaid syntax.
Flowcharts
graph TD\n A[Start] --> B{Decision?}\n B -->|Yes| C[Process]\n B -->|No| D[End]\n C --> DBasic flowchart with decision node and conditional paths
graph LR\n A --> BA[Rectangle]\nB(Rounded)\nC{Diamond}\nD((Circle))\nE>Flag]\nF[/Parallelogram/]\nG[\\Database/]\nH((fa:fa-user User))Node shapes: rectangle, rounded, diamond, circle, flag, parallelogram, database, with icons
A --> B\nA -.-> C\nA ==> D\nA -- text --> E\nF -.text.-> G\nH ==text==> I
Arrow types: solid, dotted, thick, with text labels on different arrow styles
subgraph "User Interface"\n A[Login] --> B[Dashboard]\nend\nsubgraph "Backend"\n C[API] --> D[Database]\nend\nB --> C
Group related nodes in subgraphs with cross-group connections
A --> B\nB --> C\nC --> D\nD --> A\nstyle A fill:#f9f,stroke:#333,stroke-width:4px\nstyle B fill:#bbf,stroke:#333,stroke-width:2px
Custom styling for nodes with colors and stroke widths
Sequence Diagrams
sequenceDiagram\n participant U as User\n participant F as Frontend\n participant B as Backend\n U->>F: Login Request\n F->>B: Validate Credentials\n B-->>F: Auth Token\n F-->>U: Success
Basic sequence with participant aliases and message flow
A->>+B: Request\nB->>+C: Forward\nC-->>-B: Reply\nB-->>-A: Response\nNote right of A: User waits\nNote over B,C: Processing
Activation boxes with +/- for lifeline control and notes
loop Every minute\n A->>B: Heartbeat\nend\nalt Success\n B->>A: OK\nelse Failure\n B->>A: Error\nend\nopt Cache Available\n A->>A: Use Cache\nend
Control structures: loop, alt/else, opt for conditional flows
par Parallel Task 1\n A->>B: Process 1\nand Parallel Task 2\n A->>C: Process 2\nend\nB->>A: Result 1\nC->>A: Result 2
Parallel processing with par/and blocks
Class Diagrams
classDiagram\n class Animal {\n +String name\n +int age\n +makeSound() void\n -String species\n }\n class Dog {\n +bark() void\n }\n Animal <|-- DogClass definition with visibility modifiers (+public, -private, #protected)
class BankAccount\n BankAccount : +String owner\n BankAccount : +BigDecimal balance\n BankAccount : +deposit(amount)\n BankAccount : +withdrawal(amount)
Alternative class syntax with colon notation
Customer ||--o{ Order : places\nOrder ||--|{ LineItem : contains\nProduct ||--o{ LineItem : orderedRelationships: inheritance (|--), composition (--*), aggregation (--o), association (--)
State Diagrams
stateDiagram-v2\n [*] --> Idle\n Idle --> Active : start\n Active --> Processing : process\n Processing --> Idle : complete\n Processing --> Error : fail\n Error --> Idle : reset\n Active --> [*] : terminate
State transitions with labeled triggers and final states
state Processing {\n [*] --> Validating\n Validating --> Saving\n Saving --> [*]\n}Composite states with internal state machines
Entity Relationship Diagrams
erDiagram\n CUSTOMER {\n string name\n string email\n int customer_id PK\n }\n ORDER {\n int order_id PK\n int customer_id FK\n date order_date\n }\n CUSTOMER ||--o{ ORDER : placesER diagram with entities, attributes, primary keys (PK), and foreign keys (FK)
CUSTOMER ||--o{ ORDER : "1 to many"\nORDER }|--|| PRODUCT : "many to 1"\nCUSTOMER }o--o{ PRODUCT : "many to many"Different relationship cardinalities with labels
Gantt Charts
gantt\n title Project Timeline\n dateFormat YYYY-MM-DD\n section Planning\n Requirements :done, req, 2024-01-01, 2024-01-15\n Design :active, design, 2024-01-10, 2024-01-25\n section Development\n Frontend :dev1, after design, 30d\n Backend :dev2, after design, 25d
Project timeline with sections, tasks, dependencies, and status
User Journey
journey\n title User Shopping Experience\n section Discovery\n Visit Homepage: 5: User\n Browse Products: 3: User\n View Details: 4: User\n section Purchase\n Add to Cart: 5: User\n Checkout: 2: User\n Payment: 3: User, System\n Confirmation: 5: User, System
User journey mapping with satisfaction scores (1-5) and actors
Git Diagrams
gitgraph\n commit\n commit\n branch develop\n checkout develop\n commit\n commit\n checkout main\n merge develop\n commit
Git branching and merging visualization
Resources
Complete Mermaid guide and tutorials
Official online editor
Source code and examples
Detailed flowchart documentation
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