diagram-design vs Mermaid
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
Open source · MIT
An agent skill that draws editorial diagrams as one self-contained HTML + SVG file.
Open source · MIT
Generate diagrams from Markdown-like text, for docs and code.
Our verdict
These tools solve different problems rather than competing head-on. Diagram Design is an AI agent skill: you describe a diagram in plain words and a supported coding agent produces a single HTML/SVG file, which suits teams that want brand-matched, editorial-looking visuals. Mermaid is a text-based diagram renderer: you write diagram code in a Markdown-like syntax that lives alongside your docs and code, which suits teams that want diagrams versioned as plain text.
Pick diagram-design if you already use a supported AI coding agent and want polished, brand-styled diagrams you can open in a browser without learning a diagram language.
Pick Mermaid if you want diagrams stored as editable text inside your Markdown docs and code, rendered by a tool that works in places like GitHub.
| Key difference | diagram-design | Mermaid |
|---|---|---|
| How you create diagrams | Describe the diagram in plain words; an AI agent writes it | Write diagram code in a Markdown-like text syntax |
| Output | One self-contained HTML + SVG file, opens by double-clicking | Text definitions rendered by the Mermaid renderer |
| Requirements | A supported AI coding agent such as Claude Code, Codex, Cursor, or Copilot | Learn the Mermaid syntax for each diagram type |
| Visual control | Can match your site's palette and fonts after onboarding | Layout and styling limited by what the syntax supports |
| Best at | Editorial-style visuals and redrawing existing Mermaid, draw.io, or Excalidraw files | Version-controlled diagrams kept in docs alongside code |
Written with AI from both products' catalogue entries · updated 2026-10-29
Who each one is for
Choose diagram-design if you need…
- Developers who already use a supported coding agent and want architecture or flow diagrams without learning a diagram language
- Teams that want diagrams to follow their own brand colors and fonts
- People who want diagrams they can open by double-clicking, with no server needed
- Anyone who wants to import existing Mermaid, draw.io, or Excalidraw files and redraw them
Choose Mermaid if you need…
- Developers who want diagrams stored as text alongside their code and docs
- Teams whose documentation is written in Markdown and needs diagrams
- Non-programmers who want to make diagrams using the Live Editor
- Projects that generate documentation as part of a build or production script
Side-by-side
| diagram-design | Mermaid | |
|---|---|---|
| Type | AI model / agent | Dev tool |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 64.2k | 91k |
| Setup difficulty | Beginner | Beginner |
| How you get it | Install with a package manager | Install with a package manager |
| Main language | HTML | TypeScript |
| Last code update | 5 days ago | 4 days ago |
What each one is
diagram-design
Diagram Design is a skill you add to a coding agent such as Claude Code, Codex, Cursor, or GitHub Copilot. You describe the diagram you want in plain words, and the agent produces a single HTML file containing SVG that you can open in a browser. The README says it supports 45 diagram types and can match your site's palette and fonts after you run an onboarding step.
Mermaid
Mermaid is a JavaScript tool that turns short text descriptions into diagrams such as flowcharts and sequence diagrams. You write the diagram in a Markdown-inspired syntax and the renderer draws it, so the diagram can be edited as plain text. Its stated purpose is to keep documentation up to date with development.
Best for
diagram-design
- Developers who already use a supported coding agent and want architecture or flow diagrams without learning a diagram language
- Teams that want diagrams to follow their own brand colors and fonts
- People who want diagrams they can open by double-clicking, with no server needed
- Anyone who wants to import existing Mermaid, draw.io, or Excalidraw files and redraw them
Mermaid
- Developers who want diagrams stored as text alongside their code and docs
- Teams whose documentation is written in Markdown and needs diagrams
- Non-programmers who want to make diagrams using the Live Editor
- Projects that generate documentation as part of a build or production script
Strengths
diagram-design
- Output is one self-contained HTML and SVG file that opens without extra tooling
- Works across many agent hosts, with installation steps documented for each
- Licensed under MIT
Mermaid
- Diagrams are plain text, so they are easy to edit, diff, and version-control
- Works inside tools such as GitHub, according to the README
- Large, active open-source project with a published documentation site
Not ideal for
diagram-design
- People without a supported AI coding agent, since the project is delivered as an agent skill and the README does not describe a standalone app
- Anyone who needs live, collaborative diagram editing, which the README does not mention
- Teams that need a fully manual drag-and-drop editor, because the agent chooses the diagram type and writes the file
Mermaid
- People who need pixel-precise, freeform illustration; the README describes it as text-defined diagrams rendered by a renderer
- Users who need a visual drag-and-drop editor as their main workflow, since the README centers on text input via the Live Editor
Trade-offs
diagram-design
- The README does not state a release version, so update behavior depends on each host's install path
- Quality and type choice depend on the agent that runs the skill, which the README does not evaluate
- Some install paths (such as the Cowork organization marketplace) require extra setup like mirroring the repository
Mermaid
- Layout and styling are controlled by the renderer, so fine visual control is limited by what the syntax supports
- Requires learning the Mermaid syntax for each diagram type
Getting started
diagram-design
Install the skill with the cross-agent skills CLI
npx skills add cathrynlavery/diagram-designAdd the Claude Code plugin marketplace
/plugin marketplace add cathrynlavery/diagram-designFrequently asked questions
Should I use diagram-design or Mermaid?
These tools solve different problems rather than competing head-on. Diagram Design is an AI agent skill: you describe a diagram in plain words and a supported coding agent produces a single HTML/SVG file, which suits teams that want brand-matched, editorial-looking visuals. Mermaid is a text-based diagram renderer: you write diagram code in a Markdown-like syntax that lives alongside your docs and code, which suits teams that want diagrams versioned as plain text. Pick diagram-design if you already use a supported AI coding agent and want polished, brand-styled diagrams you can open in a browser without learning a diagram language. Pick Mermaid if you want diagrams stored as editable text inside your Markdown docs and code, rendered by a tool that works in places like GitHub.
What is the difference between diagram-design and Mermaid?
diagram-design: An agent skill that draws editorial diagrams as one self-contained HTML + SVG file. Mermaid: Generate diagrams from Markdown-like text, for docs and code. diagram-design suits developers who already use a supported coding agent and want architecture or flow diagrams without learning a diagram language, while Mermaid suits developers who want diagrams stored as text alongside their code and docs.
Are diagram-design and Mermaid free?
diagram-design: Free and open source. Mermaid: Free and open source.
Is diagram-design or Mermaid more popular?
Mermaid has more GitHub stars (91k) than diagram-design (64.2k). Popularity isn't the same as fit — check which one matches your use case above.
What are other alternatives to diagram-design and Mermaid?
Other options people compare them with include Excalidraw, drawio-skill, fireworks-tech-graph, Kami, Taste Skill.
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.