Transom Diagrams · Confluence Cloud

Diagrams as text. Rendered inside Atlassian.

Write PlantUML or Mermaid in Confluence. See the diagram as you type. Your diagram source never leaves your site.

Free for sites with up to 10 users. Paid tiers include a 30-day free trial.

Source · Mermaid

flowchart TD
  A([Request]) --> B{Authenticated?}
  B -- yes --> C[Load dashboard]
  B -- no --> D[Sign in]
  C --> E([Done])

PreviewIllustration

What it does

Everything you need to draw from text.

Transom Diagrams adds one macro to Confluence. It has a split editor, a live preview and a clean view for readers.

Live preview

Edit source on the left. The diagram updates on the right as you type. Errors show the line number and a Go to line button.

PlantUML and Mermaid

One app for both. The editor detects the type from your first line. You can also switch it by hand.

10 starter templates

Flowchart, sequence, class, ER, state, Gantt and C4-style. Start from a template and change it.

Made for readers

Crisp SVG on the page. Zoom, fit to page, copy the source, or download SVG and PNG.

PDF and Word export

On save, the app attaches a PNG of your diagram to the page. Confluence PDF and Word exports show the image.

Light and dark

Diagrams follow the Confluence theme. The editor and toolbar work with a keyboard. Exports are always light on white.

Two engines

Same diagram. Your choice of syntax.

Use the language your team already knows. Both engines run in your browser, inside Atlassian's app frame.

PlantUML

@startuml
actor User
participant App
participant API
User -> App : Open page
App -> API : GET /items
API --> App : 200 OK
App --> User : Render list
@enduml

Mermaid

sequenceDiagram
  actor User
  participant App
  participant API
  User->>App: Open page
  App->>API: GET /items
  API-->>App: 200 OK
  App-->>User: Render list

PlantUML uses the built-in Smetana layout. It does not use Graphviz, so no extra component is loaded. See the limits.

Private by design

Your diagrams never leave your site.

Many diagram apps send your source to an outside server to draw it. Transom Diagrams does not.

Built on Atlassian Forge. The app runs on Atlassian's infrastructure.
No external servers. The app asks for no permission to call outside services.
No outside renderer. PlantUML and Mermaid draw in your browser. Nothing can go down on our side.
No stored copy. Your diagram source lives in the macro on your Confluence page. We hold no copy.
Built to be eligible for Runs on Atlassian. Atlassian awards the badge itself, after listing.

Read the security details

Pricing

Simple pricing by site size.

Annual prices in US dollars. Your tier follows the number of users on your Confluence site.

Transom Diagrams · price per year
Confluence site size	Per year
Up to 10 users	Free
Up to 50 users	$300
Up to 100 users	$600
Up to 300 usersA site with 250 users pays this tier.	$1,650
Up to 500 users	$2,450
Up to 1,000 users	$4,400

The free tier has every feature.
Paid tiers include a 30-day free trial on the Atlassian Marketplace.
The tier follows your Confluence site's total users, not the number of people who draw diagrams. A site between two sizes pays the next tier up.
You buy and pay through Atlassian. Annual and monthly billing are both available.
Prices are list prices. Atlassian discount programs may apply. The Marketplace shows the final price for your site.

See all tiers up to 1,000 users

Users	Per year
Up to 10	Free
Up to 15	$90
Up to 25	$150
Up to 50	$300
Up to 100	$600
Up to 200	$1,150
Up to 300	$1,650
Up to 400	$2,050
Up to 500	$2,450
Up to 600	$2,850
Up to 800	$3,600
Up to 1,000	$4,400

Larger sites: the Marketplace price calculator shows your price.

Questions

Good to know.

Does my diagram source leave my Confluence site?

No. The source is saved in the macro on your page. Your browser draws the diagram inside Atlassian's app frame. The app makes no outside requests.

Can I export a page to PDF or Word?

Yes. On save, the app attaches a PNG of the diagram to the page. Confluence uses that image in PDF and Word exports. How export works.

How large can a diagram be?

The source can be up to 100 KB. The editor tells you if you are over, and by how much. All limits.

Does it work with Confluence Data Center?

No. Transom Diagrams is for Confluence Cloud.

Can I move diagrams over from another app?

A migration helper is planned. It is not part of version 1.0. Today you can paste your PlantUML or Mermaid source into the editor.

Who do I contact for help?

Email [email protected]. See support for response targets.

Draw your first diagram in a minute.

Install from the Atlassian Marketplace. Free for sites with up to 10 users.

Get early access