Comparison · October 2026
Mermaid.ai vs Mermaid Online
Mermaid Chart rebranded to Mermaid.ai in 2026 and tightened its free tier along the way: three saved diagrams, watermarked exports, rate-limited downloads, and a small monthly AI allowance. Mermaid Online takes the opposite position — unlimited diagrams, clean exports, no rate limits, and rendering that never leaves your browser. Here is how the two stack up, fact by fact.
Unlimited diagrams · No watermark · No rate limits · Local browser rendering · Pro $5.99/mo
Side by side
as of October 2026 · verified against Mermaid.ai's public pricing and product pages
| Feature | Mermaid Online | Mermaid.ai |
|---|---|---|
| Diagrams on the free tier | Unlimited | 3 saved diagrams |
| Watermark on free exports | None | Watermarked |
| Export limits | No rate limits; PNG, SVG, JPG, WebP, PDF at 1x–4x | Rate-limited downloads on the free tier |
| Where diagrams render | Locally in your browser — code is never uploaded | In the cloud |
| AI diagram generation | Free credits to start (10 on sign-in, more via referrals); Pro includes a monthly allowance | 15 AI credits per month on the free tier |
| Cloud diagram library | 3 saved diagrams free, unlimited on Pro | Included |
| Version history | Not yet | Timeline |
| Real-time collaboration | Not yet | Included |
| Editor plugins & API | Not yet | VS Code extension, Google Docs add-on, MCP server |
| Paid plan | Pro $5.99/mo | $10–20 per user/mo |
Mermaid.ai (formerly Mermaid Chart) is the commercial arm of the Mermaid.js project, funded and feature-rich — real-time collaboration, a VS Code extension, a Google Docs add-on, and an MCP server. This page states verifiable public facts only; check both products before you decide.
Try a no-watermark export
The fastest check is your own diagram: paste the code below, export PNG or SVG at up to 4x, and compare the output with what your current tool gives you. Everything renders locally in your browser.
Export controls activate after your diagram renders locally.
FAQ
Questions about this comparison
Is Mermaid.ai free?+
It has a free tier, but in 2026 it is narrow: three saved diagrams, watermarked exports, rate-limited downloads, and 15 AI credits a month. Anything beyond that needs a paid plan at $10–20 per user per month.
What happened to Mermaid Chart?+
Mermaid Chart rebranded to Mermaid.ai in 2026. The product direction also shifted: the free tier was tightened to three diagrams with watermarks, while paid plans gained collaboration features, an MCP server, and editor plugins.
Is Mermaid Online really free without a watermark?+
Yes. Diagrams and exports are unlimited on the free plan, exports carry no watermark, and downloads have no rate limit. Pro ($5.99/mo) adds premium theme exports, a larger AI allowance, and an unlimited cloud library.
Which one should I pick?+
If you need real-time collaboration, a VS Code extension, or a Google Docs add-on, Mermaid.ai earns its subscription. If your workflow is writing Mermaid code and exporting clean images for docs, READMEs, and slides, Mermaid Online does that for free — with no watermark, no diagram cap, and no rate limits.
Does Mermaid Online upload my diagram code?+
No. Rendering and export happen locally in your browser. Cloud features — the diagram library, AI generation, share links — are opt-in, and plain converting never sends the code anywhere.
Is Mermaid Online affiliated with Mermaid.js or Mermaid.ai?+
No. Mermaid Online is an independent tool and is not affiliated with Mermaid.js, Mermaid Chart, Mermaid.ai, or their maintainers.