Does Slack support Mermaid? What works today

Direct answer: No. Slack has no built-in Mermaid renderer: Mermaid in a message, a snippet or a Canvas shows up as code. To see a diagram, use a Slack app that renders Mermaid. Arialine renders pasted Mermaid (via /arialine, an @arialine mention or a shared .mmd file) into a PNG and an interactive HTML file in the channel, and keeps the source so the team can edit it later.

What Slack does with Mermaid today

• Messages: a ```mermaid block is formatted as code. Slack also escapes characters such as > and &, which breaks arrows like -->> if you copy the code back out.
• Snippets and files: a .mmd file is shown as text.
• Canvases: Markdown-style code blocks stay code; there is no Mermaid renderer.
• Slack AI: it can read the code but does not draw it.

Ways to get a rendered Mermaid diagram into Slack

1. Render elsewhere and upload an image. Works, but the source and the image separate immediately.
2. Use a renderer app such as Mermaid Preview (/mermaid → PNG).
3. Use Arialine, which renders Mermaid and keeps it editable:
4. /arialine → paste Mermaid → Create,
5. @arialine + a Mermaid block,
6. share a .mmd file,
7. or put Mermaid blocks in a Markdown file and let Arialine turn it into a Slack Canvas with rendered diagrams.

Valid Mermaid is rendered as written, without an AI model. Arialine unescapes Slack's HTML entities first, so arrows survive.

Why "rendered" is not enough

A picture answers "what does it look like now?". Teams also ask "what changed, who asked for it, and how do I change it again?". Arialine keeps the board's source and adds each addressed change in the thread as a version, with Undo and Rewind. Read how to create and edit Mermaid diagrams in Slack for the full walkthrough.

FAQ

Will Slack add Mermaid support?

Slack has not announced native Mermaid rendering. Until it does, rendering comes from apps.

Can I render Mermaid in a Slack Canvas?

Not natively. Arialine's Markdown-to-Canvas renders each Mermaid block as an embedded image in the Canvas.

Can I create Mermaid without writing it?

Yes. Describe the diagram to @arialine in plain language and it writes the Mermaid for you.