Mermaid alternative · 2026
Mermaid is the easiest way to put a diagram in Markdown, and GitHub renders it for free. When the diagram is a system architecture that needs vendor icons, a layout you control and a picture that stays current, paste your Mermaid block below and see it redrawn.
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Generate the kind of diagram you'd build in Mermaid: free, in your browser, no account.
No account needed · Editable canvas, not a picture
Mermaid’s architecture diagram type ships five generic icons (cloud, database, disk, internet, server); vendor logos need an Iconify icon pack registered by whatever renders the page. Datadef draws with 2,000+ official AWS, Azure, GCP and data-tool icons out of the box, inside zones for accounts, VPCs and subnets.
In Mermaid you arrange text and the renderer places the boxes, so on a large system crossing edges are hard to fix from the source. Mermaid Chart’s visual editor helps for flowcharts, sequence, class, state and ER diagrams, but not for the architecture type. In Datadef you drag nodes where they belong, and repo sync keeps the positions you set.
A Mermaid block is as current as the last person who regenerated it. Mermaid Chart’s VS Code extension can draft one from your code through GitHub Copilot and offer a one-click update when sources change, from someone’s editor. Datadef’s repo sync runs on its own every day, redraws only on structural changes, and every live embed follows the canvas.
| Feature | Datadef | Mermaid |
|---|---|---|
| Source lives as text in the repo | ||
| Renders natively in GitHub Markdown | Live embed image, one markdown line | |
| Official AWS, Azure, GCP icons | 2,000+, built in | 5 generic, more via Iconify packs |
| Drag-and-drop editing of architecture diagrams | Visual editor skips the architecture type | |
| Sequence, state and Gantt diagrams | ||
| Diagram from a plain-English prompt | 1 AI diagram a day free, unlimited on Pro | Mermaid AI, limited on the free plan |
| Generated from the code in a repository | Repo sync, daily, unattended (Pro) | In VS Code, through GitHub Copilot |
| Pricing | Free daily AI; Pro $8/mo billed yearly | Library free; Mermaid Chart paid per user |
Want the full head-to-head? Datadef vs Mermaid, head to head →
Stay with Mermaid if:
Yes. Paste the Mermaid source into the prompt, say which cloud it runs on, and the AI redraws it as an editable canvas with the matching icons and zones. It is an AI redraw, not a line-by-line parser, so check the labels on a large diagram. SQL DDL and Prisma schemas are the inputs Datadef parses exactly.
No. Datadef exports PNG and JPEG and serves a live embed image; there is no Mermaid or text export. If a diagram has to stay reviewable text in the repository, keep that one in Mermaid.
Pro includes live embeds: one markdown image line renders the current diagram in a README, Notion or Confluence, and readers need no account. Edit the canvas, or let repo sync redraw it, and every embedded copy follows.
Mermaid is the open-source JavaScript library that GitHub renders. Mermaid Chart is the commercial editor built around it, now at mermaid.ai, with a visual editor, Mermaid AI, and a free plan limited to three diagrams. This page compares Datadef with both.
The scratch canvas at datadef.io/scratch is free with 1 AI diagram and 2 AI edits a day, manual editing and PNG, JPEG and JSON export, no account needed. Pro adds unlimited AI under fair use, saved projects, repo sync, live embeds, sharing and MCP for $12 a month or $96 a year, after a 7-day free trial.
Free scratch canvas, no account, no credit card: 1 AI diagram and 2 AI edits a day. Pro unlocks unlimited AI, saved projects, repo sync, live embeds and MCP for $12 a month or $96 a year, after a 7-day free trial.
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