Your last Mermaid Editor

Visualize Mermaid code as
fast as your AI writes it.

AI coding agents generate and maintain complex system architectures directly in code. Sirenetta is the dedicated native macOS companion for humans.

Coming Soon to Mac App Store

macOS 14+ Sonoma & Sequoia · Universal Binary (Apple Silicon & Intel) · Pricing: Free to try · $12.99 CAD

Designed for speed. Engineered for developer clarity.

Sirenetta split-pane Mermaid code editor and live rendered architecture diagram

Watches .mmd & Markdown via native NSFilePresenter. Diagrams update the millisecond your AI agent writes to disk.

Sirenetta Options Inspector showing live Mermaid theme, look, and layout controls

Tune Mermaid themes, look modes, curve styles, and layout spacing interactively with zero manual frontmatter syntax.

Sirenetta rendering complex Sankey flow diagrams with 100% upstream Mermaid parity

Built directly on the unmodified official Mermaid engine—supporting Sankey flows, C4, sequence, ER, and all 30+ diagram types.

Sirenetta built-in Mermaid template chooser gallery

Jumpstart system architectures, state machines, ER schemas, and user journeys from ready-to-edit native templates.

Sirenetta macOS Finder Quick Look extension previewing a Mermaid diagram directly in Finder

Hit Spacebar on any .mmd or Markdown file in Finder to inspect crisp rendered diagrams instantaneously.

Engineered for Performance & Privacy

Built for how software engineers work today.

Forget heavy browser tabs and awkward drag-and-drop web tools. Sirenetta gives your Mac a responsive, native studio tailored for modern developer workflows.

Built for AI Coding Agents

In the AI era, agents generate and refactor diagrams as code. Sirenetta watches your local files and instantly updates diagrams with zero flicker as your AI streams changes.

External File Sync Zero Manual Refresh Debounced Live Watcher

Built on the Official Mermaid Engine

Sirenetta renders with the official, unmodified Mermaid engine. New Mermaid releases arrive with app updates.

Unmodified Core All 30+ Diagram Types Official Themes & Directives

Local-First & Private

Your files never leave your Mac. Diagrams render locally, nothing is uploaded, and Sirenetta collects no data.

Works Offline No Telemetry

Vector and Bitmap Export

Generate vector SVGs with embedded fonts, or transparent PNGs. Perfect for engineering PRs, architecture design docs, Slack announcements, and keynote presentations.

Pure Vector SVG Transparent PNG

Why Sirenetta

Edit diagrams where they live.

Diagrams in Markdown are hard to edit and visualize in your IDE. Sirenetta edits them in place, in the file, with a native editor.

Web Tools & Electron

✕ Manual Copy-Paste: Copying code from your editor to a browser tab and back.
✕ Cloud Upload: Pasting private architecture diagrams into third-party web tools.
✕ Limited Styling Options: Most tools don't expose all Mermaid options.
✕ Fragile Visual Nodes: Dragging nodes by hand that break when the diagram code changes.

The Sirenetta Way

✓ Live File Sync: Changes other tools make to your .mmd or Markdown file show up automatically.
✓ Private: Your files never leave your Mac.
✓ Official Mermaid Engine: Standard Mermaid syntax, themes and directives.
✓ Code-First Fidelity: Edit the code directly in the native editor; the file stays the source of truth.

Universal Mermaid Engine

All Mermaid diagram types, rendered natively.

Because Sirenetta builds on the official Mermaid engine rather than a simplified parser, all the diagram types that Mermaid ships are available, from flowcharts and sequence diagrams to ER, Gantt, Sankey and mind maps.

Flowcharts (TD / LR / RL) Sequence Diagrams Class Diagrams State Machines Entity Relationship (ER) GitGraph Release Trees Mindmaps C4 Architecture Context User Journey Maps Gantt Timelines Sankey & XY Charts Architecture & Packet Quadrant Charts ...and many more

macOS Ecosystem Integration

Feels right at home on your Mac.

Crafted in Swift and AppKit to look and feel like an integral part of macOS Sonoma and Sequoia.

Finder Quick Look

Select any .mmd or .mermaid file in Finder and tap Spacebar to preview rendered vector diagrams immediately without opening a window.

Markdown Hub

Sirenetta registers for .md and Markdown files, letting you open, edit, and inspect diagram fences (```mermaid) embedded within your project documentation in place without touching the prose.

Native Shortcuts & Tabs

Full support for macOS window tabs, native title-bar proxy icons, pinch-to-zoom gestures, and standard shortcuts (⌘E to export, ⌘0 to reset view).

Frequently Asked Questions

Everything you need to know.

Sirenetta is purposefully designed for the modern AI development era. When AI coding agents generate and refactor diagrams, manual node positioning on a canvas is easily overwritten and breaks the code's source-of-truth. Sirenetta lets agents modify diagrams cleanly via code, allows manual code tweaks when needed, and provides fluid pan/zoom inspection without fragile visual canvas layers.

No. Sirenetta wraps the official, unmodified Mermaid core engine. Because the core parser and renderer are not modified, Sirenetta stays in 100% lockstep with every upstream Mermaid release, including new diagram types, syntax enhancements, and theme options.

Yes! Sirenetta features a built-in syntax-highlighted code editor with line numbers, AST diagnostics, and instant preview. While it excels at watching AI-generated disk updates, you can type, edit, and experiment directly inside the editor anytime.

100% local-first. Sirenetta never sends your diagram code or metadata to any remote server or third-party cloud. All parsing and rendering execute locally on your Mac, making it ideal for confidential enterprise architectures and private codebases.

Sirenetta is a Universal binary for macOS 14.0 (Sonoma) and macOS 15.0+ (Sequoia) running natively on Apple Silicon (M1/M2/M3/M4) and Intel Macs.

Visualize Mermaid code as fast as your AI writes it.