Image links

Where nothing runs plotdown and you cannot commit a file, such as an issue or pull request comment, a chat message, an email or a Notion page, link an image from plotdown.cc: the URL holds the block, and the service draws it as an SVG or a PNG.

![Penguin body mass](https://plotdown.cc/svg/pako:eNqFUz1PwzAU3PkVlieQP…)

The block is compressed and written in the URL (pako: and base64url, as mermaid.ink and Kroki do). The service stores nothing. A URL always draws the same image, so caches keep it for good.

Get a link

In the playground: choose what Copy image link copies (Markdown (SVG), SVG link or PNG link), then press it. It refuses a block with a mistake, and a block too long for a URL.

With the CLI, from a block kept in a file of its own (*.plotdown.json), from standard input, or from each block of a Markdown file in turn:

npx @devlooped/plotdown link chart.plotdown.json              # https://plotdown.cc/svg/pako:…
npx @devlooped/plotdown link --png --scale 2 -m readme.md     # ![Title](https://plotdown.cc/png/pako:…?scale=2), one per block

In a Markdown file, in place of committed SVG files: plotdown render --link puts an image link after each block, and removes the SVG files an earlier run wrote for that file:
```
```plot
{"title": "Penguins", "marks": [ … ]}
```
![Penguins](https://plotdown.cc/svg/pako:eNodyTsKwCAQ…) 
```
Add --png for PNG links. A second run changes nothing; a changed block gets a new link.
From code: imageLink(block, {format, theme, scale}) and markdownImage(url, alt) of @devlooped/plotdown/link, which runs in Node and in browsers.

SVG or PNG

	SVG (`/svg/…`)	PNG (`/png/…`)
Shown by	GitHub, GitLab, Gitea, most Markdown pages, browsers	Everything that shows images: Slack, Discord, Teams, email clients, Notion
Light and dark	Follows the reader (`?theme=auto`, the default), or `?theme=light`, `?theme=dark`	Fixed: `light` (default) or `?theme=dark`
Size	Sharp at any size	`?scale=2` (or 3, 4) for high-density screens

A block that cannot be drawn gets an image that says why, with the JSON path of the mistake. For a block too long for a URL (about 8,000 characters), the link is refused: commit an SVG file instead, or POST the block to https://plotdown.cc/svg or /png.

Links or committed SVG files

Prefer committed SVG files (plotdown render, or the GitHub Action) for a README and documentation in a repository:

They do not depend on a service. A link shows nothing if plotdown.cc is down or gone; a file in the repository stays.
The data stays with the file. A link carries the whole block, data included, to whoever opens it, and to the service, its logs and the image proxies on the way. Do not put in a link what you would not publish.
Long blocks fit. A file has no length limit.

Links are for the places where no file can go: comments, chats, email, a tool that only takes an image URL. They need no CI and no write access.

The service

https://plotdown.cc/svg/… and /png/… are open to everyone, without a key, with a rate limit per address. The service never fetches anything: a block with a data URL or a remote image is refused. Its routes, limits and error codes are in the service's readme, with how to run it yourself (plotdown link --base-url <your service>).

Note

Tried on 2026-11-12: plotdown link and plotdown render --link installed from the packed npm package, and https://plotdown.cc/svg/pako:… answering the SVG of the link they wrote. The playground's button and the rendering in Slack or email were not tried.

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