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Mermaid Diagram Renderer

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INPUT

Auto Process

OUTPUT

Client Side

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Guide

Mermaid Diagram Renderer

Paste mermaid.js syntax and instantly see a live, interactive diagram you can copy or download. Supports flowcharts, sequence diagrams, Gantt charts, pie charts, class diagrams, and more — all rendered client-side in your browser, with no servers, accounts, or installs required.

Mermaid is great for “diagrams as code”: your diagram lives next to the rest of your project as plain text, but humans need a renderer to actually see the picture. This tool fills that gap — drop in any mermaid snippet, switch themes, and export the result as SVG or PNG.

How to Use

Paste your mermaid code into the editor — or click Flowchart, Sequence, Gantt, Pie, or Class to load a starter example.
Pick a theme (Default, Dark, Forest, Neutral, Base) and a background (Transparent, White, Light gray, Dark) to match your slide deck or doc.
Watch the diagram update live as you type. If your syntax is off, you’ll get the exact mermaid error message right under the preview.
When it looks right, hit Download SVG for a perfectly scalable vector, Download PNG for a raster screenshot, or Copy to grab the SVG source for embedding.

Features

Live preview – diagram re-renders as you edit, with a debounce so big diagrams stay snappy.
All major mermaid types – flowcharts, sequence, Gantt, pie, class, ER, state, journey, and any other syntax mermaid v11 supports.
5 built-in themes – Default, Dark, Forest, Neutral, and Base, plus configurable preview backgrounds for transparent, white, light, or dark.
SVG and PNG export – download a crisp vector SVG or a 2x-scale PNG without leaving the page.
Copy-ready SVG source – grab the raw markup to paste into a README, doc, or web page.
Inline error reporting – mermaid syntax errors are shown clearly so you can fix them in seconds.
Privacy-first – everything runs in your browser. Your diagrams never touch our servers.

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 FAQ

What is mermaid.js?

Mermaid is an open-source JavaScript library that turns plain-text diagram definitions into SVG diagrams. It was created so that engineers, technical writers, and product teams could keep diagrams under version control alongside their code instead of maintaining binary files in a separate design tool. Mermaid supports many diagram types out of the box, from simple flowcharts to entity-relationship and Gantt charts.
Why use diagrams as code instead of a drawing app?

Diagrams written as text live in your repo, diff cleanly in pull requests, and update instantly when the underlying ideas change. They are searchable, scriptable, and never go out of sync with the codebase the way a screenshot in a wiki does. Visual drawing tools are great for one-off slides, but for living documentation a text-based format scales much better with your team.
What is the difference between SVG and PNG when exporting a diagram?

SVG is a vector format — it stores shapes and text as math, so it stays sharp at any size and is tiny in file size for typical diagrams. PNG is a raster format that stores a fixed grid of pixels, which makes it a safe choice for tools that do not support SVG (older slide decks, some chat apps, image-only platforms). For docs, web pages, and modern slide tools, SVG is almost always the better choice.
How do mermaid themes affect rendering?

A mermaid theme is a set of default colors and typography rules applied to the rendered diagram. The Default theme is bright and works well on light backgrounds, Dark inverts colors for dark UIs, Forest uses green tones, Neutral is grayscale, and Base is a stripped-down baseline you can override with theme variables. Switching themes only changes the look of the SVG — the underlying diagram structure stays the same.
Is rendering done locally or on a server?

Rendering happens entirely in your browser using mermaid's JavaScript engine. Nothing is uploaded, sent to a server, or stored remotely. That keeps confidential architecture diagrams private and means the tool keeps working even on a slow or offline network connection.