Help & Instructions - Sequence Diagram Maker | Collaborative Mermaid Diagram Editor

What is This Tool?

This is a collaborative Mermaid diagram editor - a free online tool that lets you create and edit diagrams using Mermaid syntax with real-time collaboration. Mermaid is a JavaScript-based diagramming and charting tool that renders Markdown-inspired text definitions to create diagrams dynamically.

While this guide focuses on sequence diagrams (one of the most popular diagram types), our editor supports all Mermaid diagram types, including:

Sequence Diagrams - Show how objects interact in a particular sequence over time
Flowcharts - Visualize processes, workflows, and decision flows
Class Diagrams - Document object-oriented system structures
State Diagrams - Model state machines and transitions
Entity Relationship Diagrams (ERD) - Design database schemas
User Journey Diagrams - Map user experiences and interactions
Gantt Diagrams - Create project timelines and schedules
Pie Chart Diagrams - Visualize proportional data
Quadrant Charts - Organize items in a 2x2 matrix
Requirement Diagrams - Document system requirements
GitGraph Diagrams - Visualize Git branching strategies
C4 Diagrams - Model software architecture at different levels
Mindmaps - Create hierarchical information structures
Timeline Diagrams - Show chronological sequences of events

All diagram types support real-time collaboration, making this the perfect collaborative diagram tool for teams working on documentation, system design, or any visual communication needs.

Getting Started with Our Mermaid Diagram Editor

Step 1: Open the Mermaid Diagram Editor

Navigate to our collaborative Mermaid diagram editor to start creating diagrams online. No sign-up or installation required - just open the website and begin. You can create any type of Mermaid diagram, from sequence diagrams to flowcharts, class diagrams, and more.

Step 2: Write Your Diagram Code

Type your diagram code in the editor using Mermaid syntax. The editor supports all Mermaid diagram types. For example, to create a sequence diagram, start with sequenceDiagram. For a flowchart, start with flowchart TD or flowchart LR. Our editor supports real-time collaboration, so multiple team members can work together simultaneously on the same diagram.

Example: Basic Sequence Diagram

sequenceDiagram
    participant A as Alice
    participant B as Bob
    A->>B: Hello Bob, how are you?
    B-->>A: Great!
    A->>B: Let's collaborate on a diagram
    B->>A: Perfect! I'll join your room

Step 3: Preview Your Diagram

Watch your diagram render in real-time in the preview panel as you type. The live preview feature ensures you see exactly how your diagram will look before sharing or exporting, whether it's a sequence diagram, flowchart, class diagram, or any other Mermaid diagram type.

Step 4: Share and Collaborate

Click the Share button to get a room URL and invite team members to collaborate on your diagram in real-time. Our collaborative diagram tool supports multiple users editing simultaneously with instant synchronization, perfect for team diagramming sessions.

Step 5: Export Your Diagram

Download your diagram as SVG (vector format) or PNG (raster format) for use in documentation, presentations, or other projects. SVG format is ideal for documentation and scaling, while PNG is great for presentations.

Example: Basic Flowchart

flowchart TD
    A[Start] --> B{Decision}
    B -->|Yes| C[Action 1]
    B -->|No| D[Action 2]
    C --> E[End]
    D --> E

Features of Our Mermaid Diagram Editor

Real-time Collaboration

Multiple users can edit diagrams simultaneously with instant synchronization. Perfect for team diagramming and collaborative diagramming sessions on any Mermaid diagram type.

All Mermaid Diagram Types

Create professional diagrams using Mermaid syntax with live preview. Supports sequence diagrams, flowcharts, class diagrams, state diagrams, ER diagrams, Gantt charts, pie charts, mindmaps, timelines, and more.

Auto-save Functionality

All diagrams are automatically saved, so you never lose your work. Diagrams are stored for 30 days after creation.

Shareable Room URLs

Easily share your collaborative diagram sessions with team members via unique URLs. No account creation required.

SVG and PNG Export

Download your sequence diagrams in high-quality SVG or PNG formats. Perfect for documentation, presentations, and technical specifications.

Live Preview

See your sequence diagram update in real-time as you type the Mermaid code. No need to manually refresh or compile.

Free to Use

Completely free online Mermaid diagram editor with no sign-up required. Create unlimited diagrams of any Mermaid type - sequence diagrams, flowcharts, class diagrams, and more.

Full Mermaid Syntax Support

Complete support for all Mermaid diagram syntax including flowcharts, sequence diagrams, class diagrams, state diagrams, ER diagrams, Gantt charts, pie charts, mindmaps, timelines, GitGraph, C4 diagrams, and more. See Mermaid examples for inspiration.

Creating Sequence Diagrams with Mermaid Syntax

Basic Sequence Diagram Elements

Our sequence diagram tool supports all standard Mermaid sequence diagram syntax:

Participants: Define actors or objects in your sequence diagram using participant keyword
Messages: Use ->> for synchronous messages and -->> for asynchronous messages
Activations: Show when an object is active using activate and deactivate
Notes: Add annotations with Note over or Note right/left of
Loops and Alt blocks: Use loop, alt, opt, and par for control structures

Advanced Sequence Diagram Example

sequenceDiagram
    participant User
    participant Frontend
    participant API
    participant Database

    User->>Frontend: Login Request
    Frontend->>API: Authenticate User
    API->>Database: Query User Data
    Database-->>API: Return User
    API-->>Frontend: Auth Token
    Frontend-->>User: Welcome Page

    Note over User,Database: Complete authentication flow

Collaborative Diagramming Features

Real-time Collaboration

Our collaborative diagram tool supports real-time collaboration, allowing multiple team members to edit the same diagram simultaneously, whether it's a sequence diagram, flowchart, class diagram, or any other Mermaid diagram type. Changes sync instantly across all connected users, making it perfect for team diagramming sessions.

Room-based Collaboration

Each diagram session is assigned a unique room. Share the room URL with your team members to start collaborating. All participants see each other's changes in real-time, with visual indicators showing who is editing what.

No Account Required

Unlike other collaborative diagramming tools, our Mermaid diagram editor doesn't require account creation. Simply share the room URL and start collaborating immediately on any type of diagram.

Use Cases for Mermaid Diagrams

Software Architecture Documentation

Create sequence diagrams, class diagrams, and C4 diagrams for software architecture documentation. Our online Mermaid diagram editor makes it easy to document API flows, microservice interactions, system structures, and communication patterns.

API Design and Documentation

Use sequence diagrams to document API request/response flows, authentication sequences, and error handling scenarios. Flowcharts can visualize API decision trees. Perfect for technical documentation and developer onboarding.

System Design Discussions

Collaborate with your team on system design using our collaborative diagram tool. Create flowcharts for processes, class diagrams for object models, state diagrams for behavior, and ER diagrams for database design. Real-time collaboration makes it easy to iterate on designs and get immediate feedback from team members.

Project Management

Use Gantt diagrams for project timelines, user journey diagrams for UX planning, and mindmaps for brainstorming sessions. All diagram types support real-time collaboration.

Technical Specifications

Include various diagram types in technical specifications to clearly illustrate system interactions, workflows, data models, and architectures. Export as SVG for high-quality documentation.

Frequently Asked Questions

What is this tool?

This is a collaborative Mermaid diagram editor - a free online tool that lets you create and edit diagrams using Mermaid syntax with real-time collaboration. Mermaid is a JavaScript-based diagramming tool that supports many diagram types including sequence diagrams, flowcharts, class diagrams, state diagrams, ER diagrams, Gantt charts, pie charts, mindmaps, timelines, and more.

How do I create a collaborative diagram?

To create a collaborative diagram, simply open our Mermaid diagram editor, start typing your Mermaid code (e.g., sequenceDiagram for sequence diagrams, flowchart TD for flowcharts), and click the Share button to get a room URL. Share this URL with your team members to collaborate in real-time on the same diagram.

Is this diagram tool free?

Yes, our online Mermaid diagram editor is completely free to use. There's no sign-up required, and you can create unlimited diagrams of any Mermaid type - sequence diagrams, flowcharts, class diagrams, state diagrams, ER diagrams, Gantt charts, and more.

What types of diagrams can I create?

You can create all Mermaid diagram types including sequence diagrams, flowcharts, class diagrams, state diagrams, entity relationship diagrams, user journey diagrams, Gantt diagrams, pie charts, quadrant charts, requirement diagrams, GitGraph diagrams, C4 diagrams, mindmaps, and timeline diagrams. All diagrams support real-time collaborative editing. See Mermaid examples for inspiration.

Can multiple people edit a diagram at the same time?

Yes, our collaborative diagram tool supports real-time collaboration. Multiple team members can edit the same diagram simultaneously, with changes syncing instantly across all connected users.

How do I export my diagram?

You can export any diagram (sequence diagram, flowchart, class diagram, etc.) as SVG (vector format) or PNG (raster format) by clicking the Download button in the preview panel. SVG format is ideal for documentation and scaling, while PNG is great for presentations.

Do I need to install anything to use this Mermaid diagram editor?

No installation required. Our online Mermaid diagram editor runs entirely in your web browser. Just open the website and start creating diagrams immediately - whether it's a sequence diagram, flowchart, class diagram, or any other Mermaid diagram type.

Are my diagrams saved automatically?

Yes, all diagrams are automatically saved to the database. Diagrams are stored for 30 days after creation, and you can access them anytime by using the same room URL. Important: If you need to keep your diagrams for longer than 30 days, you should manage the code yourself by copying the Mermaid code from the editor and saving it to your own storage (local file, version control, cloud storage, etc.). The 30-day limit helps keep the service clean and secure.

Can I use this Mermaid diagram editor offline?

The Mermaid diagram editor requires an internet connection for real-time collaboration features. However, you can work on diagrams locally and they will sync when you reconnect.

What makes this different from other diagram tools?

Our Mermaid diagram editor is completely free, requires no sign-up, supports real-time collaboration, and uses the powerful Mermaid syntax which supports many diagram types. Unlike desktop applications, it's accessible from any device with a web browser. Unlike other online tools, it supports all Mermaid diagram types, not just one or two.

Tips for Creating Better Diagrams

Choose the Right Diagram Type

Select the appropriate Mermaid diagram type for your needs: sequence diagrams for interactions over time, flowcharts for processes, class diagrams for object structures, state diagrams for behavior, ER diagrams for databases, etc.

Keep It Simple

Focus on the most important elements. Too many components can make any diagram hard to read. Break complex systems into multiple diagrams if needed.

Use Meaningful Names

Give elements clear, descriptive names that explain their purpose. This applies to participants in sequence diagrams, nodes in flowcharts, classes in class diagrams, etc.

Add Notes for Clarity

Use notes and annotations to explain complex interactions or provide context that isn't obvious from the diagram itself. Mermaid supports notes in sequence diagrams and labels in other diagram types.

Organize with Control Structures

Use appropriate control structures: loop, alt, and opt in sequence diagrams; decision nodes and subgraphs in flowcharts; relationships in class and ER diagrams.

Collaborate Early

Share your diagrams with team members early in the design process to get feedback and catch issues before implementation. Real-time collaboration makes this easy.

Learn Mermaid Syntax

Familiarize yourself with Mermaid syntax for different diagram types. The syntax is intuitive and Markdown-inspired, making it easy to learn.

Keyboard Shortcuts

Ctrl/Cmd + S: Share room URL
Ctrl/Cmd + Enter: Format diagram code
Escape: Exit fullscreen mode
Tab: Indent in editor

Additional Resources

Mermaid.js Official Documentation - Complete reference for Mermaid syntax
Mermaid Sequence Diagram Syntax - Detailed guide to sequence diagram syntax
GitHub Repository - Open source collaborative Mermaid diagram editor