Paste a PlantUML `@startuml` block into the online editor, watch the live preview update as you type, pick a theme for the look, and export sleek, modern SVG or HD PNG. No account required — activity diagrams, sequence, swimlanes, class, and state all render live in the same PlantUML editor online.
Each sample is a real PlantUML source — paste it into the editor and the live preview shows the beautified render immediately. Click Open in editor on any sample to load it without copy-pasting.
A reimbursement approval with three lanes and a rejection branch. Type the activity grammar on the left, watch the lane layout render live on the right.
@startuml
|Employee|
start
:Submit reimbursement;
|Manager|
:Review request;
if (Approved?) then (yes)
|Finance|
:Process payment;
else (no)
|Employee|
:Receive rejection;
endif
stop
@endumlIncident response with `|#Color|Lane|` syntax. Each colour hint maps to a theme-coherent palette so the lanes read cleanly on light or dark documentation backgrounds.
@startuml
|#FFB6C1|Monitoring|
start
:Alert fires;
|#FFE4B5|On-call|
:Acknowledge alert;
:Initial diagnosis;
if (Known issue?) then (yes)
:Run runbook fix;
else (no)
|#B0E0E6|SRE Lead|
:Apply fix;
endif
stop
@endumlThree actors, sync calls, async returns. The editor renders lifelines and message arrows live so you can see the timing read clearly while you edit.
@startuml
participant Client
participant API
participant Auth
Client -> API: GET /profile
API -> Auth: validate(token)
Auth --> API: 200 OK + user
API --> Client: 200 OK + profile
@endumlUser, Order, Product with one-to-many associations. PlantUML class syntax is verbose but the editor's live preview makes it easy to verify your relationships visually as you type.
@startuml
class User {
+id: string
+email: string
+login()
}
class Order {
+id: string
+total: number
+submit()
}
class Product {
+sku: string
+price: number
}
User "1" --> "*" Order : places
Order "*" --> "*" Product : contains
@endumlPaste, preview, and export from the online PlantUML editor without signing up — anonymous sessions never persist server-side.
Type PlantUML source on the left and the rendered diagram updates on the right in real time, all inside the same online editor.
Beauty Diagram parses PlantUML in our own engine — your `@startuml` source is not relayed to a third-party PlantUML server, so internal diagrams stay confidential.
Download sleek, modern SVG with fonts inlined, or HD PNG sized for docs, decks, and tickets — straight from the online PlantUML editor.
Activity (with `|lane|` swimlanes, `if-else`, `repeat-while`, `switch-case`), sequence, class, state, and component diagrams all parse and render live. Activity and swimlane receive bespoke beautified layout; class / state / component use a more general pass and will gain dedicated layouts in later releases.
No. Anonymous use covers unlimited preview, beautify, and SVG / PNG export with a small watermark. An account on the free plan removes the watermark and saves diagrams to a personal hub.
No. Beauty Diagram parses PlantUML source in our own engine — your `@startuml` block does not leave our infrastructure to be processed by a third-party PlantUML server. That keeps internal diagrams confidential and removes the round-trip that some online PlantUML tools have.
Yes. Paste any PlantUML source — including `@startuml` / `@enduml` blocks copied from a `.puml` or `.txt` file — straight into the editor. Both standalone source and fenced markdown blocks are accepted.
The official web editor at plantuml.com uses the reference renderer — accurate but the output looks dated for modern docs and slide decks. Beauty Diagram parses the same source but renders it with theme-matched palettes, horizontal swimlane columns, and orthogonal cross-lane edges. Same source, sleek, modern output, plus SVG / PNG export without manual styling.
The PlantUML editor opens with a live preview, theme picker, and clean SVG / PNG export. No sign-up.