Free Diagram Maker — Generate PNG and SVG from Mermaid, PlantUML, and D2
Render 16+ diagram languages — Mermaid, PlantUML, D2, Graphviz, C4 (Structurizr), WaveDrom, and more — live in the browser. Generate flowcharts, sequence diagrams, ER diagrams, Gantt charts, and network diagrams from code and download them as PNG or SVG. No sign-up required, completely free.
Why write diagrams as code?
Compared to drag-and-drop tools like Visio or draw.io, code-based diagrams offer three key advantages.
1. **Git version control** — diagram changes appear in pull requests 2. **Text editor support** — work in VS Code, Vim, or any editor 3. **Reusability** — templatize and share a consistent style across the team
Especially powerful for engineering teams' architecture diagrams, operations flowcharts, and API sequence diagrams.
Supported diagram languages
· **Mermaid**: flowcharts, sequence diagrams, ER diagrams, Gantt charts, pie charts — embeds directly in Markdown · **PlantUML**: full UML — class diagrams, use case diagrams, activity diagrams · **D2**: modern declarative language (2023). Great for architecture diagrams · **Graphviz (DOT)**: the classic for graph theory. Handles dense node/edge diagrams · **Structurizr DSL**: C4-model software architecture in layers · **WaveDrom**: digital circuit timing waveforms · **TikZ, Vega-Lite, and 10 more**
Should I use SVG or PNG?
**SVG** is a vector image — it scales without degrading. Use SVG for documents and web pages; it's also text-searchable.
**PNG** is raster. Use it when pasting into Slack or Notion (which handle SVG poorly) or when embedding in Word or PowerPoint.
Both formats are one-click downloads — choose which to save after rendering.
Want to auto-generate diagrams with AI?
If you'd rather describe your diagram in plain language ("draw a user registration flow", "visualize sequences between microservices"), the **AI Diagram Maker** (premium feature) selects the best notation and generates code for you. Give it a try before wrestling with syntax.