Introducing line9

We built line9 because existing Mermaid renderers produce diagrams that are hard to read, poorly laid out, and visually inconsistent. line9 takes the same Mermaid syntax you already know and produces significantly better output.

Why another Mermaid renderer?

Mermaid is the most widely used text-to-diagram language. It’s embedded in GitHub, Notion, Obsidian, and dozens of other tools. But the default renderer has real limitations:

• Overlapping labels on complex flowcharts
• Inconsistent spacing that makes large diagrams hard to follow
• No semantic zoom — every node gets the same treatment regardless of importance

line9 solves these problems with a rendering engine built from scratch, focused on layout quality above all else.

Jump straight to the diagram viewer to try it yourself.