Trellis is a diagram renderer optimized for Mermaid-compatible diagrams, designed to produce clean, overlap-free orthogonal SVG layouts. It supports flowchart, class, ER, C4, and architecture diagram types, ensuring professional-grade visualizations without manual adjustments.
Key Features:
Mermaid Compatibility: Renders standard Mermaid syntax with no migration required.
Clean Layouts: Uses custom routing to eliminate tangled edges and overlapping nodes.
Multi-Format Support: Outputs diagrams as SVG, PNG, HTML, and Draw.io files for versatile use cases.
Command-Line Interface (CLI): Enables automation and integration into workflows via winget or direct commands.
Winget Deployment: Install Trellis directly on Windows using winget install trellislab.trellis.
Target Audience and Benefits:
Ideal for developers, technical writers, and architects seeking to create professional diagrams quickly. Trellis ensures clear visualizations that enhance documentation and presentations without manual tweaking, saving time and effort in diagram creation.
Trellis is a drop-in replacement for the default Mermaid renderer. It produces clean, overlap-free diagrams — no tangled edges, no manual layout tweaking, no post-processing in a drawing tool.
→ trellislab.net — live comparison and interactive editor
Why Trellis
Standard Mermaid uses an aging layout engine that frequently produces diagrams with overlapping and crossing edges. The result is diagrams that are hard to read and not presentation-ready without significant manual effort.
Trellis replaces that engine. Every edge finds its own clear corridor. Diagrams come out clean the first time.
Standard Mermaid syntax. Zero migration. Existing .mmd files work without changes.
Supported diagram types
Flowchart
Class diagram
Entity-relationship (ER)
C4 architecture diagram
Architecture (architecture-beta) — with icon support (AWS and other Iconify sets)
Installation
VS Code extension
Install from the marketplace:
ext install trellislab.trellis-mermaid
Or search "Trellis" in the VS Code Extensions panel. Live preview updates as you type.
Trellis includes a Pandoc Docker image for rendering Markdown documents with embedded Mermaid diagrams directly to PDF or HTML — no pre-processing step, no local Trellis install required.
Two separate licenses apply, covering different things:
Source in this repository (docs, MCP server wrapper, provisioning scripts, examples) — MIT License.
Trellis CLI binary and Docker images — proprietary, closed-source. See the EULA. Trellis is free for everyday rendering; render-batch and MCP SVG/HTML/Draw.io output are commercial features that require a license key.