Render Mermaid diagramslive in your IDE
Open a Markdown file, see every mermaid block in a side panel — toggle between diagram and source, live-refresh as you type. No browser tab. No network. No copy-paste.
JetBrains IDEs 2023.3+ · IntelliJ IDEA, PyCharm, WebStorm & more · JCEF required
Available now — v0.1.2
Every diagram, renderedwhere you already are
Auto-detect every block
Scans all fenced ```mermaid``` blocks in your Markdown file and renders each as its own card in the side panel. Open a 500-line doc with 8 diagrams and see them all at once — no scrolling required.
Per-block toggle
UniqueEach card has a segmented Diagram ↔ Code button. Flip between the rendered output and the raw Mermaid source in one click without losing your place in the editor.
Live refresh as you type
Diagrams re-render with a 250ms debounce as you edit. No save required, no manual refresh button, no context switch. Watch your sequence diagram or flowchart evolve in real time.
Theme-aware rendering
Follows your IDE's dark or light theme automatically via JCEF. No jarring white boxes in a dark-theme IDE. Switch themes and the webview adapts instantly.
Fully offline — Mermaid bundled
Mermaid 10.9.3 is packed inside the plugin zip. No CDN calls, no internet connection, no corporate firewall issues. Works on planes, trains, and air-gapped enterprise environments.
12+ diagram types
Flowchart, sequence, state machine, class, entity-relationship, Gantt, pie, git graph, user journey, mindmap, quadrant chart, timeline — the full Mermaid surface area supported out of the box.
Why does previewing a diagram take four steps?
You write a mermaid block, select all, copy, alt-tab to mermaid.live, paste, wait for it to render, squint at the result, alt-tab back, edit, and repeat. Every time. The IntelliJ Markdown plugin does not render mermaid fences — it just shows the raw text. Browser extensions help but they live outside your IDE.
Mermaid Preview puts the rendered diagram right next to your code, updates as you type, and never leaves your IDE. The copy-paste loop stops the moment you install it.
See it for yourself
Real screenshots from IntelliJ IDEA with the plugin installed.
Stop alt-tabbing to mermaid.live
The preview you need is already in your IDE — you just had to install one plugin.
JCEF webview,
mermaid bundled inside
The plugin uses JCEF — the same Chromium-based webview JetBrains uses for its own DevTools. A DocumentListener fires on every keystroke, debounced to 250ms, calling MermaidBlockExtractor which parses the fences and sends a JSON payload to the embedded preview.html.
Mermaid 10.9.3 is bundled inside the plugin zip — no CDN, no network call, no corporate proxy to fight. The webview reads the IDE theme token and switches between dark and light mermaid themes automatically.
```mermaid
sequenceDiagram
Alice ->> Bob: Hello Bob
Bob ->> Alice: Hi Alice
Alice ->> Bob: Got a minute?
```
// ↑ type this in your .md file
// ↓ see this in the Mermaid panel
rendered sequence diagram appears
in the right sidebar instantly ✨Up and running in 4 steps
Works in any JetBrains IDE — same steps everywhere.
Download the zip
Click the Download button below to get the latest zip from GitHub Releases.
Open plugin settings
In your JetBrains IDE: Settings → Plugins → ⚙ gear icon → Install Plugin from Disk…
Settings → Plugins → ⚙ → Install Plugin from Disk…
Select the zip and restart
Pick the downloaded zip, click OK, then restart the IDE when prompted.
Open any Markdown file
Open a .md file with ```mermaid fenced blocks — the Mermaid panel appears automatically on the right sidebar.
Supported IDEs
Any IDE built on the IntelliJ Platform 2023.3+ with JCEF enabled
v0.1.2 · 2026-05-09 · MIT license · JetBrains IDEs 2023.3+
Past releases →Coming to JetBrains Marketplace
Roadmap v0.5Right now you install from a zip file. That works fine, but the JetBrains Marketplace means one-click install directly from your IDE — no zip download, no manual steps, and automatic updates whenever a new version ships.
- ✅ Install directly from Settings → Plugins → Marketplace
- ✅ Automatic updates — always on the latest version
- ✅ Listed in the official JetBrains plugin directory
Get notified on release
A note from Slothy
Help us
please! ☕
100% open sourceMermaid Preview is free. No strings attached.
Mermaid Preview is open source — every line is on GitHub. Zero tracking. Zero telemetry. No paywalls, no accounts, no subscription. Install the zip and you're done.
Mermaid Preview runs on spare time. There's no VC money, no subscription, no ads. Just a team building on nights and weekends. If you find it useful, a coffee goes a long way.
All SlothLabs apps — MIT license, zero telemetry, all source on GitHub
Stop alt-tabbing to mermaid.live
Free JetBrains plugin. Install in 4 steps. Works in every IntelliJ-based IDE.
Free forever · JetBrains IDEs 2023.3+ · MIT license
Past releases →