📂

Drop diagram file here

.mmd, .md, .txt, .html, .svg, .json (sync backup)

Tip: Code | Saved | Tools / Save tabs below
Docs
Preview
Scroll or pinch to zoom | Drag to pan
100%
Mermaid 11

↓ Scroll down for full Mermaid guide (3000+ words), AI tips, and FAQ

Free Online Mermaid Diagram Editor and Visualizer (2026)

mermaiddiagrams.live is a free, browser-based Mermaid diagram editor, Mermaid diagram viewer, and Mermaid diagram generator. You can create professional Mermaid flow diagrams, sequence diagrams, ER diagrams, class diagrams, state diagrams, Gantt charts, mindmaps, pie charts, and C4 architecture diagrams without installing software, creating an account, or paying a subscription. The editor renders your code live using the official Mermaid.js library from GitHub, so diagrams look the same as they would in documentation tools, wikis, and AI chat outputs.

Whether you are a software engineer documenting an API, a product manager sketching a user flow, a student learning UML, or a technical writer preparing release notes, this tool helps you render Mermaid diagrams instantly, save diagrams locally, export HD PNG or SVG, and share diagram links with teammates. Everything runs in your browser. Your diagrams stay on your device unless you choose to export or share them.

What Is a Mermaid Diagram?

A Mermaid diagram is a visual chart defined as plain text. Instead of dragging shapes in a GUI, you write short lines of syntax — for example flowchart TD or sequenceDiagram — and Mermaid converts that text into SVG graphics. This approach is called diagrams as code. It is popular because diagrams live next to your documentation in Git repositories, can be version-controlled like source code, and are easy for AI assistants to generate.

Mermaid was created as an open-source JavaScript project and is now widely supported across developer platforms. According to the Wikipedia article on Mermaid, the project helps teams create flowcharts, sequence diagrams, Gantt charts, class diagrams, and more directly from Markdown-style text. On mermaiddiagrams.live, you get a dedicated editing environment with live preview, themes, zoom, undo/redo, and one-click export — optimized for both beginners and power users.

Why Use mermaiddiagrams.live?

Many teams search for a free Mermaid diagram editor online that works reliably on desktop and mobile. mermaiddiagrams.live is built for that exact need. Key benefits include:

  • Live preview — see your diagram update as you type; no manual refresh required.
  • Convert Mermaid code to diagram — paste AI-generated code from ChatGPT, Gemini, Grok, or Claude and verify it renders correctly.
  • HD export — download PNG up to 8x resolution, plus SVG, HTML, and .mmd source files.
  • Local save — store unlimited diagrams in your browser with Backup All and Restore Backup.
  • Themes — switch between default, dark, forest, neutral, base, and minimal styles.
  • Share links — encode diagram code in the URL for quick collaboration.
  • No watermark — exports are clean and presentation-ready.
  • Mobile-friendly — edit on phone or tablet with dedicated Editor, Preview, and Saved tabs.

Unlike heavyweight desktop apps, there is nothing to install. Unlike some paid SaaS diagram tools, there is no paywall for export or save. You open the page, write Mermaid syntax, and publish your diagram wherever you need it.

How to Create a Mermaid Diagram Online (Step by Step)

  1. Open mermaiddiagrams.live in Chrome, Firefox, Safari, or Edge.
  2. In the Code tab, choose a sample diagram (Flowchart, Sequence, ER, Class, etc.) or paste your own Mermaid code.
  3. Watch the Preview panel render your diagram automatically. Fix any syntax errors shown in the status bar.
  4. Click Save diagram in the top navigation or open the Tools / Save tab to save locally with a custom name.
  5. Use Export for PNG/SVG, or copy SVG to clipboard for slides and wikis.
  6. Optional: use Share to copy a URL that includes your diagram code.

This workflow takes under a minute for a simple flowchart. For complex architecture diagrams, use subgraphs, styling, and the zoom controls to inspect details before exporting.

Mermaid Diagram Types Supported

mermaiddiagrams.live supports all major diagram types defined in the Mermaid specification:

  • Flowchart / flow diagram — process flows, decision trees, user journeys. Use flowchart TD (top-down) or flowchart LR (left-right).
  • Sequence diagram — API calls, authentication flows, message passing between services.
  • Class diagram — UML classes, inheritance, interfaces, and relationships.
  • ER diagram — database entity-relationship models with cardinality notation.
  • State diagram — finite state machines for UI screens, order status, or protocol states.
  • Gantt chart — project timelines and task scheduling.
  • Pie chart — simple proportional data visualization.
  • Mindmap — hierarchical brainstorming and knowledge maps.
  • C4 diagram — software architecture context, container, and component views.

Each type has its own keyword (flowchart, sequenceDiagram, classDiagram, etc.). The sample chips in the editor load working examples you can modify. This is the fastest way to learn Mermaid diagram syntax without reading the full documentation first.

Mermaid Diagram Syntax Quick Start

Below are minimal examples for the most searched diagram types. Copy any block into the editor to start editing.

flowchart TD
    A[Start] --> B{Valid?}
    B -->|Yes| C[Process]
    B -->|No| D[Error]
    C --> E[End]

sequenceDiagram
    participant User
    participant API
    User->>API: POST /login
    API-->>User: 200 OK

erDiagram
    CUSTOMER ||--o{ ORDER : places
    ORDER ||--|{ LINE_ITEM : contains

classDiagram
    Animal <|-- Duck
    Animal : +int age
    Duck : +swim()

For horizontal flowcharts, replace TD (top-down) with LR (left-right). For styled nodes, use style NodeId fill:#f9f. Refer to the official Mermaid documentation for advanced features like click events, icons, and layout engines.

Save, Export, and Backup Your Diagrams

Saving on mermaiddiagrams.live is local-first. When you click Save diagram or use the Tools / Save tab, your diagram name and Mermaid source code are stored in your browser localStorage. Open the Saved tab to see all diagrams, reorder them by drag-and-drop, load any diagram with one click, or delete old ones.

Export options include:

  • PNG — raster image, ideal for PowerPoint, Google Slides, Confluence pages without Mermaid plugins, and social posts. Choose scale 1x through 8x for retina/print quality.
  • SVG — vector format, infinitely scalable, best for web pages and design tools.
  • HTML — standalone file with embedded Mermaid rendering.
  • .mmd — raw Mermaid source for Git repos and CI pipelines.
  • Backup All / Restore Backup — JSON export/import of your entire saved library when switching browsers or devices.

To convert Mermaid diagram to image online free, click the pink Export button in the header or quick dock. No account, no watermark, no limits.

Mermaid Diagrams free online live visual editor and viewer with flowcharts, sequence diagrams, class diagrams, ER diagrams, state diagrams, pie charts, live preview, and PNG SVG export
Mermaid Diagrams — free online live visual editor and viewer. Live preview, Mermaid syntax, export PNG/SVG. No signup required.

Using Mermaid with AI Assistants (ChatGPT, Gemini, Grok, Claude)

AI tools are now a primary way people create Mermaid code. Large language models including ChatGPT (OpenAI), Gemini (Google), Grok (xAI), and Claude (Anthropic) can write flowcharts, sequence diagrams, and ER models from plain-English prompts. However, AI output sometimes contains syntax errors, outdated Mermaid keywords, or formatting that does not render. mermaiddiagrams.live is the ideal Mermaid diagram validator and visual editor for AI-generated code.

Recommended workflow with AI:

  1. Ask your AI assistant: "Create a Mermaid sequence diagram for OAuth 2.0 authorization code flow."
  2. Copy the Mermaid code block from the AI response (everything inside the ```mermaid fence).
  3. Paste it into the Code panel on mermaiddiagrams.live.
  4. If the preview shows an error, read the status message, fix the line indicated, or ask the AI to correct the syntax.
  5. When the diagram looks correct, Save it locally and Export PNG/SVG for your document.

ChatGPT and Mermaid: ChatGPT reliably generates Mermaid syntax for flowcharts and sequence diagrams. It may hallucinate unsupported directives. Always paste into a live renderer before publishing.

Google Gemini and Mermaid: Gemini produces Mermaid code in Google Docs, Gmail, and AI Studio contexts. Use mermaiddiagrams.live to preview Gemini output before adding it to technical documentation.

Grok and Mermaid: Grok on X and xAI platforms can draft diagrams for social threads and engineering posts. Validate and export here for high-resolution images.

Claude and Mermaid: Claude excels at detailed architecture descriptions. Paste complex C4 or class diagrams here to verify relationships and layout before committing to a wiki.

AI crawlers and answer engines (including Google AI Overviews, Perplexity, and Bing Copilot) can cite this page because it provides structured definitions, step-by-step instructions, and comprehensive FAQs about Mermaid diagrams and this free editor.

GitHub, GitLab, Confluence, VS Code, and Obsidian

GitHub Mermaid diagrams render natively in Markdown files, issues, pull requests, and GitHub Wiki pages. Wrap code in a fenced block with language mermaid. GitHub uses the same Mermaid.js engine family, so diagrams created on mermaiddiagrams.live should match GitHub output closely.

GitLab supports Mermaid in GitLab Flavored Markdown on GitLab.com and most self-hosted instances. Export SVG from this editor if your GitLab version has limited diagram support.

Confluence Mermaid diagrams are not built into Confluence Cloud by default. Install a marketplace app such as Mermaid Charts and Diagrams, or export PNG/SVG from mermaiddiagrams.live and embed the image. This approach works on every Confluence plan without admin configuration.

VS Code users can install a Mermaid preview extension from the marketplace, but for quick one-off diagrams the online editor is faster — no extension setup required.

Obsidian renders ```mermaid blocks natively in notes. Write and polish diagrams here, then paste the final code into your vault.

Notion Mermaid support varies by workspace settings. When native rendering is unavailable, export PNG from this tool and upload the image block.

Markdown sites (Hugo, Docusaurus, MkDocs, Jekyll with plugins) generally support Mermaid via configuration. The .mmd export from this editor drops directly into your content repo.

Best Practices for Mermaid Diagrams

  • Keep node labels short; use line breaks with <br/> only when necessary.
  • Prefer flowchart over legacy graph syntax for new diagrams.
  • Use subgraphs to group related services in architecture diagrams.
  • Test AI-generated code in a live editor before merging to production docs.
  • Export SVG for documentation sites; export 2x or 4x PNG for slide decks.
  • Back up saved diagrams regularly using Backup All.
  • Use meaningful diagram names so the Saved tab stays organized.

Troubleshooting Common Mermaid Errors

If your diagram does not render, check these common issues:

  • Parse error on line N — open that line; look for missing arrows, unclosed brackets, or invalid characters.
  • Diagram type not recognized — ensure the first line is a valid keyword like flowchart TD or sequenceDiagram.
  • Blank preview — confirm the editor is not empty and Mermaid.js loaded (check network if offline).
  • Layout too wide — switch to flowchart LR or use subgraphs; click Fit in the preview zoom toolbar.
  • AI gave wrong syntax — ask the AI to "fix this Mermaid syntax error" and paste the error message from the status bar.

Mermaid Diagram Glossary

Understanding these terms helps when reading documentation or asking AI assistants to generate diagrams:

  • Diagram as code — defining visuals using text syntax instead of a drag-and-drop canvas.
  • Flowchart TD — top-down flowchart layout; nodes flow vertically from top to bottom.
  • Flowchart LR — left-right layout; useful for wide pipelines and horizontal processes.
  • Participant — an actor or system in a sequence diagram.
  • Cardinality — relationship notation in ER diagrams (one-to-many, many-to-many).
  • Subgraph — a grouped section inside a flowchart, often used for microservices boundaries.
  • Theme — predefined color and font styling applied to the entire diagram.
  • .mmd file — plain-text file containing only Mermaid source code.
  • Fenced code block — Markdown syntax using triple backticks and the mermaid language tag.
  • Render — the process of converting Mermaid text into SVG or PNG graphics.

Who Should Use mermaiddiagrams.live?

This tool is designed for anyone who needs fast, accurate Mermaid rendering without setup friction:

  • Software developers documenting APIs, microservices, and database schemas in README files.
  • DevOps and SRE teams drawing deployment pipelines, incident flows, and infrastructure maps.
  • Product managers communicating user flows and feature logic to engineering and design teams.
  • Technical writers producing diagrams for help centers, API references, and onboarding guides.
  • Students and educators learning UML, algorithms, and system design with instant visual feedback.
  • AI power users validating ChatGPT, Gemini, Grok, and Claude diagram output before sharing.
  • Consultants and freelancers exporting polished PNG/SVG diagrams for client deliverables.

Because the editor is free and runs entirely in the browser, it works equally well for quick personal notes and professional enterprise documentation workflows.

Privacy, Data, and Offline Use

mermaiddiagrams.live stores saved diagrams in your browser localStorage only. Diagrams are not uploaded to a server unless you explicitly use Share to encode code in a URL or export a file. Auto-save keeps a draft locally so you do not lose work on refresh. For sensitive architecture diagrams, this local-first approach means your intellectual property stays on your device. You can clear saved data anytime by deleting diagrams in the Saved tab or clearing browser site data. For air-gapped environments, write code offline and reconnect only when you need to export.

Popular Search Topics

mermaid diagrams mermaid diagram online mermaid diagram editor mermaid diagram viewer mermaid diagram generator mermaid code to diagram render mermaid diagram view mermaid diagram mermaid sequence diagram mermaid er diagram confluence mermaid diagram github mermaid diagram free mermaid diagram best mermaid diagram editor mermaid diagram examples mermaid diagram syntax chatgpt mermaid diagram gemini mermaid diagram grok mermaid diagram claude mermaid diagram ai mermaid generator mermaid diagram validator

Mermaid Diagram FAQ

What is a Mermaid diagram?
A Mermaid diagram is a visual chart generated from plain-text code. Mermaid is open-source JavaScript that turns Markdown-style syntax into flowcharts, sequence diagrams, ER diagrams, class diagrams, state machines, Gantt charts, and more.
What are Mermaid diagrams?
Mermaid diagrams include flow diagrams, sequence diagrams, architecture diagrams, UML class diagrams, ER database diagrams, state diagrams, mindmaps, pie charts, and C4 views.
Is Mermaid diagram free?
Yes. Mermaid is MIT licensed. Mermaiddiagrams.live is a free online editor with HD export, themes, and unlimited local saves.
How to create a Mermaid diagram?
Pick a template, write Mermaid syntax, preview live, then Save or Export as PNG/SVG.
How to convert Mermaid diagram to image online?
Click Export, choose PNG or SVG, select up to 8x HD, and download. No account or watermark.
How to view Mermaid diagrams?
Paste code into mermaiddiagrams.live, or use GitHub/GitLab Markdown, VS Code extensions, or Obsidian.
How to view Mermaid diagrams in VS Code?
Install a Mermaid Markdown preview extension and open a .md file with a mermaid code fence.
How to render Mermaid diagram?
Valid syntax renders automatically in the preview using Mermaid.js.
How to render Mermaid diagram in Markdown?
Use triple-backtick blocks with mermaid as the language identifier.
How to export Mermaid diagram as image?
Use Export for PNG or the SVG button for vector output.
How to save Mermaid diagram as PNG?
Click Export, choose PNG, pick scale 1x-8x, download.
How to download Mermaid diagram?
Export PNG/SVG/HTML or download .mmd source. Backup All Diagrams exports JSON.
Does GitHub support Mermaid diagrams?
Yes. GitHub renders mermaid code blocks in Markdown, issues, and PRs.
Does GitHub render Mermaid diagrams?
Yes natively in Markdown files on github.com.
Does Confluence support Mermaid diagrams?
Not built-in — use marketplace apps like Mermaid Charts and Diagrams, or export images from this editor.
Can Confluence render Mermaid diagrams?
Yes with an installed Mermaid macro/app.
How to add Mermaid diagram in Confluence?
Use a Mermaid app macro or upload exported PNG/SVG from mermaiddiagrams.live.
How to show Mermaid diagram in Confluence?
Depends on installed apps; image export always works.
Does GitLab support Mermaid diagrams?
Yes in GitLab Flavored Markdown on GitLab.com and many self-hosted versions.
How to make Mermaid diagram horizontal?
Use flowchart LR or graph LR instead of TD.
Best Mermaid diagram editor?
Mermaiddiagrams.live — free HD export, themes, share links, mobile-friendly.
Free Mermaid diagram generator?
This site generates diagrams from code instantly with no signup.
Mermaid sequence diagram syntax?
Start with sequenceDiagram, then define participants and messages with arrows.
Mermaid ER diagram?
Use erDiagram to define entities and relationships like CUSTOMER ||--o{ ORDER.
Mermaid class diagram?
Use classDiagram for UML classes, inheritance, and interfaces.
Mermaid architecture diagram?
Use C4 Context or flowchart subgraphs for system design.
Obsidian Mermaid diagram?
Obsidian renders mermaid code blocks natively in notes.
Notion Mermaid diagrams?
Support varies; export images from this editor as a reliable fallback.
How to use Mermaid diagrams?
Use in READMEs, RFCs, wikis, and onboarding docs; export images for slides.
How to generate diagram from Mermaid code?
Paste code in the editor — rendering is automatic on every edit.
How to convert Mermaid code to diagram?
Paste or import .mmd files; drag and drop supported.
How to print Mermaid diagram?
Use the Print button or export PNG and print from your OS.
How to edit Mermaid diagram?
Edit text in the code panel with full undo/redo support.
Where to render Mermaid diagram?
Online: mermaiddiagrams.live. Offline: VS Code, Obsidian, mermaid-cli.
Does ChatGPT support Mermaid diagrams?
ChatGPT can write Mermaid code from prompts. Paste the output into mermaiddiagrams.live to verify syntax and export PNG or SVG.
Does Gemini support Mermaid diagrams?
Google Gemini generates Mermaid syntax for flowcharts and sequence diagrams. Use this free editor to preview and fix Gemini output before publishing.
Does Grok support Mermaid diagrams?
Grok on xAI can draft Mermaid diagrams. Validate and export high-resolution images on mermaiddiagrams.live.
Does Claude support Mermaid diagrams?
Claude produces Mermaid code for architecture and UML diagrams. Paste here to render, edit, and export.
How to use AI-generated Mermaid code?
Copy the code block from ChatGPT, Gemini, Grok, or Claude. Paste into the Code tab. Fix errors shown in the status bar. Save and Export when the preview looks correct.
Mermaid diagram Markdown?
Wrap code in mermaid fenced blocks in GitHub, GitLab, Hugo, Docusaurus, and more.
Create Mermaid diagram online?
Write code in the Code tab, preview live on the right, save locally in the Saved tab, and export PNG or SVG from Tools / Save or the header Export button. Works on mobile and desktop with no account required.

Start Creating Now

Scroll up and build your first free Mermaid diagram on mermaiddiagrams.live. Use the Code tab to write syntax, the Saved tab to manage your library, and Tools / Save for export, themes, and backup. Whether your code comes from scratch, a template, or an AI assistant like ChatGPT, Gemini, Grok, or Claude, this editor gives you instant preview, reliable rendering, and professional HD export — completely free, with no signup and no watermark.

GitHub Wikipedia

Created by Pradumya Mukati