Live demo

Try it before you install.

This runs the same diagram renderer as the extension, right here. Hover a node, click it, press / to search or P to play.

Fullscreen keys: + - zoom · / find · M map · P play · Esc close the popup

Fullscreen viewer

Every diagram gets a toolbar.

Inline, a diagram sits still in your document. Click fullscreen and it becomes something you can move around in, from the keyboard or the mouse.

/Find a node by name
MOverview map of the whole diagram
PPlay a sequence, journey or timeline
+ - 0Zoom in, zoom out, reset
EscClose the popup, then leave fullscreen

links into a nodelinks out of it

Motion

Diagrams that play.

Mermaid journeys and timelines are redrawn in one calm style and play when you ask them to. DBML, a database schema language that is not part of Mermaid, is drawn by Nimbus as well.

User journeyStages on a sentiment curve, the low point in orange.

TimelineYears spaced by elapsed time, revealed one by one.

DBML schemaA dbml code block becomes table cards. Hover a table and its keys light up.

Rendered vs explored

A diagram is more than a picture.

Mermaid draws a diagram as a static image. Nimbus keeps that inline, and adds a fullscreen viewer for when you need to read it properly.

On a diagram	Static render	Nimbus fullscreen
Zoom and move	Browser zoom only	Wheel, pinch, drag, + and -
Find a node	Ctrl+F on the page	Search by name with /
Trace connections	Follow the lines by eye	Links in blue, out in orange, with a popup
Sequences and journeys	All at once	Step by step with P
Database schemas	Not part of Mermaid	DBML drawn as table cards

Everything else

A complete Markdown reader.

Built for README files, design notes and the Markdown your AI coding agent writes.

30+ themes

Nimbus light and dark, GitHub, cleanrmd themes, or your own CSS.

Code highlighting

Prism for fenced code blocks and a highlighted raw view.

Math

MathJax for inline and display formulas.

A sidebar that follows where you are reading.

Auto reload

Save the file, the preview updates by itself.

Stays in your browser

Rendering is local. Websites work only where you allow them.

Get started

Running in a minute.

Install Nimbus Markdown from the Chrome Web Store.
Open chrome://extensions, click Details on Nimbus Markdown and turn on Allow access to file URLs.
Drag a .md file into the browser. For files on websites, add the site in Advanced Options.

# Release flow

```mermaid
flowchart LR
  pr([Pull request]) --> ci{Checks pass?}
  ci -->|yes| merge[Merge]:::focal
  ci -->|no| fix[Fix] --> pr
  merge --> tag[(Tag)] --> store([Web Store])
```

Save as flow.md, open it in Chrome and click fullscreen on the diagram.

FAQ

Questions before you install.

Why do I need to turn on "Allow access to file URLs"?

Chrome blocks every extension from reading local files until you allow it. Without that switch Nimbus can only render Markdown on websites you add. It is one toggle on the extension's Details page in chrome://extensions.

Does Nimbus upload my documents?

No. Rendering happens in your browser and your documents are not sent to a developer server. Emoji images load from a CDN, and your settings sync through your browser if sync is on. The privacy policy lists everything it handles.

Will it run on every website?

No. Website access is an optional permission. Nimbus only renders Markdown on the sites you add in Advanced Options, for example https://raw.githubusercontent.com.

Which diagrams are supported?

Every diagram type Mermaid 12 renders. Fullscreen, zoom and node search work on all of them. Sequence, state, journey and timeline diagrams also play step by step, and journey, timeline, gantt, pie, quadrant, git graph, C4, mindmap and requirement diagrams are redrawn in the Nimbus style. DBML is supported separately in dbml code blocks.

Does it work outside Chrome?

It installs from the Chrome Web Store on Chromium browsers such as Edge and Brave. A Firefox build is attached to each GitHub release, with some limits listed in the Firefox notes.

Does this website track me?

This page uses Traceway, a self-hosted service, to record each visit as an anonymous session: the page address, referrer, IP address, browser and screen size, plus a replay of how the page is used and which buttons are clicked. It sets no cookies and has no sign-in or forms. The extension itself is not tracked at all.

Is it really free?

Yes. Nimbus is MIT licensed open source, a maintained fork of Markdown Viewer by Simeon Velichkov. There is no paid tier.

Like it? Give it a star.

Nimbus is free and built in the open. A star or a review helps other developers find it.

⭐ Star on GitHub Report an issue

Mermaid diagrams you can explore, not just look at.