# PlantUML for GitHub

> Renders plantuml code blocks directly on GitHub pages using the client-side TeaVM-compiled PlantUML engine.

Canonical page: [https://chrome-stats.com/d/plantuml-for-github](https://chrome-stats.com/d/plantuml-for-github)

## Overview

- **ID:** `plantuml-for-github`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** PlantUML
- **Category:** web-development
- **Daily users:** 735
- **Weekly downloads:** 75
- **Rating:** 5.00 / 5 (2 ratings)
- **Version:** 0.2.4
- **Last updated:** 2026-05-19
- **First published:** 2026-05-15
- **Size:** 3.03 MB
- **Data as of:** 2026-09-08
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/plantuml-for-github/)
- **Website:** [https://github.com/plantuml/plantuml-for-github](https://github.com/plantuml/plantuml-for-github)

## Description

<strong>Render PlantUML diagrams natively on <a href="https://prod.outgoing.prod.webservices.mozgcp.net/v1/39c2605130c4e512cd6df6e96898250ffe7d4f087fd585ece54793b3180ef0b6/http%3A//GitHub.com" rel="nofollow">GitHub.com</a>.</strong> This extension detects
<code>plantuml</code> code blocks on any GitHub page (READMEs, issues, pull
requests, discussions, wikis) and renders them inline as SVG diagrams,
exactly the way GitHub already renders Mermaid.

<strong>No server. No tokens. No tracking. Zero permissions.</strong>

The entire PlantUML engine runs client-side inside a sandboxed iframe
shipped with the extension. Nothing is sent to a remote server, no API
keys are required, and the extension declares <strong>zero host permissions</strong>,
<strong>no storage access</strong>, and <strong>no tabs API access</strong>. It only runs on
<code><a href="https://prod.outgoing.prod.webservices.mozgcp.net/v1/18292d9c1899dd2b453ea9e3c1375587569f07a1d91694af6d865f8eab086cdb/http%3A//github.com" rel="nofollow">github.com</a></code>.

Features
<ul><li>Renders all standard PlantUML diagrams: sequence, class, component,
  deployment, state, use-case, activity, object, timing, and more.</li><li>Also recognizes the <code>puml</code> and <code>wsd</code> language aliases.</li><li>Each rendered block has a small header bar with a toggle button that
  switches between the diagram and the original PlantUML source (using
  GitHub's own syntax highlighting).</li><li>Follows GitHub's light/dark color mode automatically.</li><li>Works on issues, PRs, discussions, READMEs, wikis, and gists.</li></ul>
How it works

The TeaVM-compiled PlantUML engine is bundled with the extension and
runs entirely inside a sandboxed iframe with an opaque origin — no
network access, no shared state with the host page. The same
architecture GitHub itself uses for Mermaid.

Open source

MIT-licensed. Source code and issue tracker:
<a href="https://prod.outgoing.prod.webservices.mozgcp.net/v1/f9592d8dd3b6f45003b9519d5437469be4ead08bcfc6edabf1be4ffd813e19e2/https%3A//github.com/plantuml/plantuml-for-github" rel="nofollow">https://github.com/plantuml/plantuml-for-github</a>

## Rankings

- #3,953 — Overall
- #22 — github
- #36 — plan
- #100 — component
- #126 — gif
- #127 — iframe

## Permissions and access

### Permissions

- `clipboardWrite`

### Content script matches

- `github.com`

## Safety

- **Risk impact:** High risk impact
- **Risk likelihood:** Moderate risk likelihood

### Analysis details

- Request access to the following domains: github.com
- This extension has low user count. Unpopular extensions may not be stable or safe.

> Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing).

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Source: [Chrome-Stats](https://chrome-stats.com/d/plantuml-for-github)