Free live Mermaid diagram editor with no signup required
Browse and apply curated themes for Codex Desktop on macOS and Windows
Stage
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Founded
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Based in
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Pricing model
Free
Freemium
Pricing
Not given
Free: 6 published Free themes, free Plugin, offline Restore. Pro: US$9/year (Launch Sale, regularly US$19.90/year before applicable taxes), includes all 17 Pro themes, new releases, compatible updates, theme switching, and offline Restore. Renews annually until canceled. Manual refund requests withi
Key features
Live preview as you type
21 diagram types including flowcharts, sequence, class, state, ER, Gantt, git graph, mindmap and timeline
Two-way editing for flowcharts
SVG and PNG export
Share diagrams as URLs with embedded diagram content
Built-in template picker and cheatsheet
No account or signup required
Works entirely in browser with local storage
Open Mermaid Live Editor links
Mermaid v11 syntax support
Browse curated theme gallery
Apply themes from inside Codex
Switch or restore themes with confidence
Free open-source Plugin
Data-only theme packages
Automatic rollback on apply failure
Offline restore of official interface
Device authorization and approval flow
Compatible with macOS and Windows
Compatibility verification before applying themes
What makes it different
No signup, paywall, or data collection required
Diagrams stay in your browser's local storage by default
Two-way editing that updates code when you edit the canvas
Live preview with no render button required
Clean SVG export for professional use in docs and slides
Reversible and safe theme changes with offline restoration available without login or active subscription
Data-only theme packages that cannot execute code or access conversations and projects
No remote DRM or removal of appearance already on user's computer
Free themes always available plus affordable Pro subscription with new releases included
Compatibility checks and automatic rollback protect workspace integrity
FlowViz
Codex Skin