DiagramGPT
DiagramGPT is an advanced AI tool that specializes in transforming natural language into various types of graphical representations. It facilitates the generati...
Last verified:
What is DiagramGPT?
DiagramGPT is a browser-based AI diagram generator that converts natural language descriptions into professional technical diagrams and Mermaid.js code. Built around Mermaid, a popular text-to-diagram syntax, the tool allows users to create flowcharts, sequence diagrams, class diagrams, user journey maps, Gantt charts, and C4/C4C-style system diagrams simply by describing what they want in plain English.
The platform features a built-in Mermaid code editor with live preview, letting users write or paste Mermaid code and see instant visual feedback. Key capabilities include one-click editing in the official Mermaid Live editor for advanced modifications, one-click copying of Mermaid code, and SVG export for embedding diagrams in documentation, slides, or wikis. The tool is completely free to use with no sign-up requirement and uses the user's own OpenAI API key for AI generation.
DiagramGPT is designed for developers, project managers, designers, and anyone who needs quick diagrams for documentation, planning, and presentations without investing time in full-blown diagram suites like Visio or Lucidchart. The open-source project is hosted on GitHub under fraserxu/diagram-gpt, built with Next.js, shadcn UI, and Mermaid.js.
DiagramGPT pricing
Pricing model: Free
DiagramGPT is a free-to-use web application with no sign-up requirement and no paid plans advertised. The tool itself does not charge any fees. However, when generating diagrams from natural language, it uses the user's own OpenAI API key, meaning users pay OpenAI directly for any tokens consumed. There are no subscription tiers, usage-based pricing, or enterprise plans on the DiagramGPT site or GitHub.
DiagramGPT pros
- Converts natural language directly to diagrams without manual dragging
- Supports 6 diagram types: flowcharts, sequence, class, user journey, Gantt, C4C
- Built on Mermaid.js for text-based, version-control friendly diagrams
- Live preview shows diagram instantly as you edit code
- One-click export to SVG for docs, slides, and wikis
- Copy Mermaid code instantly for reuse in other tools
- One-click edit in official Mermaid Live editor for advanced editing
- No sign-up required to start using the tool
- Completely free web application with no paid plans
- Open-source codebase available on GitHub
- Lightweight alternative to heavy diagram suites like Visio
- Uses user's own OpenAI API key, so no hidden costs from the tool
- Built with modern Next.js framework and shadcn UI
- Perfect for quick documentation diagrams without learning complex tools
- Browser-based with no installation required
DiagramGPT cons
- Requires user to provide their own OpenAI API key for AI generation
- No official open-source license listed on GitHub repository
- Limited to Mermaid.js syntax only, no support for other diagram formats
- Only 6 diagram types supported, fewer than comprehensive tools
- No built-in paid plans or enterprise features like SAML SSO
- Basic editor lacks advanced styling and customization options
- No version history or diagram storage on the platform itself
- Dependent on OpenAI API availability and costs
Frequently asked questions about DiagramGPT
What is DiagramGPT and what does it do?
DiagramGPT is a browser-based AI diagram helper that converts text descriptions into clean technical diagrams and Mermaid.js code. Instead of dragging shapes around by hand, you describe your flow or system in natural language, and DiagramGPT produces the corresponding diagram including flowcharts, sequence diagrams, class diagrams, user journeys, Gantt charts, and C4/C4C-style system diagrams.
How do I use DiagramGPT to create a diagram?
Open the web app at diagram-gpt.fraserxu.dev to see the Mermaid code editor and preview panel. If prompted, add your OpenAI API key. Then either type a natural-language description of what you want (e.g., 'user logs in, system validates credentials, then redirects to dashboard') or paste/edit Mermaid code directly. The app produces Mermaid code and renders the diagram preview. Tweak the text or code to adjust nodes, labels, or flow, and regenerate as needed.
What diagram types does DiagramGPT support?
DiagramGPT supports 6 diagram types: flowcharts, sequence diagrams, class diagrams, user journey maps, Gantt charts, and C4/C4C-style system diagrams. These cover common use cases for software documentation, project planning, system architecture, and business process mapping.
Is DiagramGPT free to use?
Yes, DiagramGPT is a free-to-use web application with no sign-up requirement. The tool itself does not advertise any paid plans or usage-based pricing. However, when using the natural language generation feature, you need to provide your own OpenAI API key and pay OpenAI directly for any tokens consumed.
Do I need to sign up or create an account?
No, DiagramGPT has no sign-up requirement. You can open the web app at diagram-gpt.fraserxu.dev and start creating diagrams immediately without creating an account or logging in.
What is Mermaid.js and why does DiagramGPT use it?
Mermaid is a popular text-to-diagram syntax that lets you create diagrams using plain text code instead of visual editing. DiagramGPT is built around Mermaid.js, which means all diagrams are text-based and version-control friendly. Your diagrams are really just short snippets of code that can be copied, edited, and reused easily.
How do I export or share my diagrams?
DiagramGPT offers two export options: use 'Copy code' to grab the Mermaid definition for reuse in other tools, or use 'Copy SVG' to export the rendered diagram as a scalable image for embedding in documentation, knowledge bases, slide decks, or wikis. You can also click the 'Edit' link to jump into the Mermaid Live editor for deeper editing.
Can I edit diagrams after they're generated?
Yes, you can edit diagrams in multiple ways. Directly tweak the natural language text or Mermaid code in the built-in editor to adjust nodes, labels, or flow, then regenerate. For more advanced editing, click the 'Edit' button to open the current diagram in the official Mermaid Live editor, which provides access to more advanced editing options.
Is the DiagramGPT code open source?
Yes, the full project is available on GitHub under fraserxu/diagram-gpt. The README describes it as a web app for generating diagrams from natural language using Mermaid and Next.js. However, no explicit open-source license is currently listed on the repository.
Who should use DiagramGPT?
DiagramGPT is ideal for developers, project managers, and designers who need quick diagrams for documentation, planning, and presentations. It's perfect for anyone who wants to convert complex processes and structures into clear graphical representations quickly without investing time in full-blown diagram suites like Visio or Lucidchart.