Mermaid vs PlantUML (2026): which should you pick?
As of Nov 12, 2026, PlantUML grades higher than Mermaid: 3.0 against 2.4 out of 4.0.
Checked Oct 6, 2026 and Nov 12, 2026 · graded Oct 10, 2026 and Nov 12, 2026 by ToolGPA
Mermaid grades higher on features. PlantUML grades higher on value for money and the free plan. They get the same grade on ease of use and platforms.
Price, platforms and features side by side. The table says where each price was read and when.
Mermaid
Text-based diagramming platform with AI and a visual editor
Which one is for you
Pick Mermaid if
- Fits if you already write Mermaid syntax in your docs or Markdown
- Works for diagrams you want versioned and reviewed as text, like code
Look elsewhere if
- Skip it if you want to pay by the month, since paid plans are billed annually only
- Tight if you're staying free, with 3 diagrams on the plan card, a size limit and 15 AI credits
- Pricey if you lean on the AI, with 300 credits a year on Plus and 2,000 on Premium at $20
- Watch out: one page gives the free plan 3 diagrams on the card and 6 in the table, and the trial length isn't stated
- Not for you if you want a desktop or phone app, or free viewer seats below Premium
Pick PlantUML if
- Fits if you want diagrams stored as text next to your code
- Works for teams documenting systems in wikis or Markdown
Look elsewhere if
- Skip it if you want to drag shapes around a canvas
- Not for you if you sketch freehand, because it has no whiteboard
- Watch out: layout is decided by the engine, so fine control over placement is limited
- Watch out: only the GPL build has every feature, and other license builds lack some such as ditaa
How we grade them
| 2.4GPAMermaidFair | 3.0GPAPlantUMLVery good | |
|---|---|---|
| Value for money | CPlus is $10 a user a month against a category middle of $8.33, and it's billed annually only, so you hand over $120 up front with no monthly option. That buys 300 AI credits for the whole year, and free viewer seats wait for Premium at $20. | AFree and open source, with a jar anyone can download or an online editor. Nothing to pay, whatever the category's $5 to $10 a month. |
| Free plan and trial | CBasic is free and includes co-editing and external sharing, but the caps arrive fast: 3 diagrams on the plan card, up to 6 in the comparison table on the same page, a limited diagram size and 15 AI credits. The trial of the paid plans has no stated length. | AThe whole tool is free, under GPL, LGPL, Apache, BSD, EPL or MIT licenses, so there's no cap to hit. |
| Features | BThe diagramming job, covered: flowcharts, sequence and ER diagrams, Gantt charts and mind maps written in Mermaid syntax and laid out for you, AI drafts from a document or transcript, a visual editor that rewrites the code as you drag, plus slides and live co-editing. | CUML plus Gantt, mind maps and wireframes from text. But the FAQ admits you get less say over layout, there's no visual canvas, and non-GPL builds lose some features like ditaa. |
| Ease of use | CNo rating on record. This is a tool you learn: Mermaid syntax has its own grammar per diagram type, and the AI drafts and click-and-drag editor soften that rather than remove it. Easier if you already write Mermaid in your docs, a curve if you don't. | CYou have to learn its text language before you get a diagram, and no store rating is on record. The in-browser editor takes some of the sting out. |
| Platforms and integrations | BWeb only, with no desktop or phone app. It has plugins for VS Code, JetBrains IDEs, Cursor, Confluence, Jira, Google Docs, Word and PowerPoint, plus an MCP server so Claude or Cursor can generate diagrams. | BRuns in a browser and through a jar, with links into Confluence, MediaWiki, IntelliJ IDEA, Eclipse and GitHub. No phone app or desktop app of its own is listed. |
| Best for | diagrams you write as text, then tidy by hand | text-described UML and other diagrams |
The GPA is the average of the five grades: an A is 4 points, an F is none. The full reasons are on each tool's page: Mermaid and PlantUML. How we grade
Price against what you get
Mermaid starts at $10 a month for each person and scores 2.7 out of 4 on features, ease of use and platforms. PlantUML has no paid plan and scores 2.3.
Mermaid scores higher, and starts $10 a month higher: the question is whether the extra is worth that to you. Of the other whiteboard and mind map tools on the chart, 11 score higher than Mermaid for less, and none scores higher than PlantUML for less.
Features, ease of use and platforms, averaged
What paid plans start at, a month (each step along is roughly double) →
- The best score at each price
- Has a free plan
- No free plan
Where they differ
- PlantUML is open source, according to its own site.
- Mermaid also covers presentations.
- PlantUML also covers Gantt & timelines and mind mapping.
At a glance
| Mermaid | PlantUML | |
|---|---|---|
| Pricing | Free plan | Free |
| Starts at | $10 per user / month, billed annually ($120 a year) | Free |
| Free plan | Basic plan: 3 diagrams (the comparison table on the same page says up to 6) with a limited diagram size, 15 AI credits, one team and project, and co-editing and external sharing. | Free of charge and open source, under several license options including GPL, LGPL, Apache, BSD, EPL and MIT. |
| Free trial | Free trial of Plus or Premium; the vendor does not state how long it lasts | None listed |
| Web | ||
| Browser extension | ||
| Made by | Mermaid Chart | PlantUML |
| Price read from | mermaid.ai | plantuml.com |
| Checked | Oct 6, 2026 | Nov 12, 2026 |
Worth knowing
Mermaid
- The free Basic plan is listed as 3 diagrams on its plan card and up to 6 in the comparison table, with a limited diagram size and 15 AI credits.
- Paid plans are billed annually only; the vendor's FAQ says monthly plans are not available.
- AI credits are capped at 300 a year on Plus and 2,000 a year on Premium; only Enterprise is listed as unlimited.
- Free viewer seats start at Premium, and SSO, invoicing and a customer success manager are limited to Enterprise.
PlantUML
- Layout is controlled by the engine; the FAQ says it gives less control over placement than drag-and-drop tools.
- Diagrams are written in code, so there is no visual canvas for freehand sketching.
- Builds under licenses other than GPL lack some features, such as the ditaa integration.
Key features
Mermaid
- Diagrams from Mermaid code
- Diagrams are written in Mermaid syntax and laid out automatically. Clicking a node jumps to its code and clicking the code finds its shape, so the two stay in step.
- Mermaid AI
- A description, an uploaded document or a pasted transcript becomes a first-draft diagram, and the AI suggests a fitting diagram type. Use is metered in credits below Enterprise.
- Visual Editor
- Nodes, edges, labels, colors and shapes can be changed by clicking and dragging while the code rewrites itself, with node alignment and movable edges for tidying a layout.
- Live co-editing and share links
- Teammates can co-edit a diagram at the same time, and a share link lets other people view it without logging in. Free viewer seats are part of Premium and Enterprise.
- Plugins and MCP server
- Plugins cover VS Code, JetBrains IDEs, Cursor, Windsurf, Confluence, Jira, Google Docs, Word and PowerPoint. An MCP server lets Claude, VS Code and Cursor generate diagrams.
- Presentations
- Existing diagrams become slides written in Markdown. A deck updates when its diagrams change and can be shared through a public link for viewing and comments.
PlantUML
- Text-to-diagram language
- Diagrams are written as short text and drawn from it, so changing the text updates the picture.
- UML and non-UML diagrams
- Supports sequence, use case, class, object, activity, component, deployment, state and timing diagrams, plus Gantt, MindMap, WBS, wireframe and others.
- In-browser editor
- The home page has an editor that runs in the browser with a JavaScript rendering engine and redraws as the code changes.
- Many integrations
- The Running page lists connections to wikis and forums, editors and IDEs, including Confluence, MediaWiki, IntelliJ IDEA and Eclipse.
- Several license options
- The download page offers jars under GPL, LGPL, Apache, BSD, EPL and MIT; the GPL build is the one with every feature, such as ditaa.
Plans
Mermaid
Basic$0
3 diagrams with a limited diagram size, 15 AI credits, and one team and project. Co-editing and external sharing are included.
Plus$10
per user / month, billed annually ($120 a year)
Unlimited diagrams with no size limit and 300 AI credits per year, for individuals who diagram often.
Premium$20
per user / month, billed annually ($240 a year)
Everything in Plus, plus 2,000 AI credits per year, unlimited free viewer seats, and unlimited teams and projects.
EnterpriseCustom
Everything in Premium, plus SSO, custom contracts and invoicing, IP management, user consolidation and a dedicated customer success manager.
PlantUML
Open source$0
Free jar and source code under your choice of license; you run it yourself or use the online editor.
Common questions
Which is cheaper, Mermaid or PlantUML?
As of Nov 12, 2026, PlantUML is cheaper to start with: it is free, against $10 a month for each person for Mermaid. Mermaid starts at $10 per user / month, billed annually ($120 a year), and PlantUML is free.
Which has a free plan, Mermaid or PlantUML?
As of Nov 12, 2026, both Mermaid and PlantUML have a free plan.
Which platforms do Mermaid and PlantUML run on?
As of Nov 12, 2026, only PlantUML lists a browser extension. Both list a web app. A platform missing from a listing is one its maker's pages did not mention.
More comparisons
How this page was made
- The verdict at the top follows a fixed rule. When both tools are in the same category and either is in our top three for it, the verdict follows that ranking: the higher-placed tool is our pick. The top three weigh who each tool suits as well as its grades, so a pick can go against the GPA. Otherwise the page does not pick one and says which grades higher: the higher GPA first; on a tie, the one with a free plan, then the one that starts cheaper in dollars a month, counted the same way for both; if they are still level, what the choice depends on.
- The grades are our own, from each tool’s review or report card. The GPA is their average.
- Prices, plans and platforms come from each tool’s listing. The table above says where each price was read and when.
- The differences and the answers to the questions are worked out from those listings.