D2 vs PlantUML: Choosing the Right Diagram Language for Engineering Teams
Evaluate D2 and PlantUML diagram languages side by side. Understand syntax, collaboration workflows, CI/CD usage, and which tool accelerates engineering documentation.
D2 vs PlantUML: Choosing the Right Diagram Language for Engineering Teams
D2 and PlantUML both let you describe diagrams in plain text so they can live in version control, but they solve different problems. D2 is optimized for readable system maps that auto-layout well. PlantUML is optimized for strict UML models and fine-grained control.
Executive summary
- D2 is ideal for day-to-day architecture maps that need to stay readable over time.
- PlantUML is ideal for formal UML documentation and complex interaction modeling.
- Many engineering orgs use both: D2 for system maps and PlantUML for formal UML artifacts.
Headline differences
| Capability | D2 | PlantUML |
|---|---|---|
| Syntax style | YAML-like, indentation-friendly | Script-like with UML keywords |
| Auto layout | Strong defaults | Manual tuning via directives |
| Diagram types | System designs, cloud maps, ERDs | Full UML suite, sequence, deployment |
| Best fit | Product delivery squads | Enterprise architecture groups |
Syntax comparison
D2 system diagram
app: Web App
api: API Service
queue: Message Queue
worker: Background Worker
app -> api: REST calls
api -> queue: Publish events
queue -> worker: Consume
PlantUML component diagram
@startuml
package "Web App" as App
node "API Service" as API
queue "Message Queue" as MQ
component "Background Worker" as Worker
App --> API : REST calls
API --> MQ : Publish events
MQ --> Worker : Consume
@enduml
Takeaway: D2 favors compact, readable structure. PlantUML favors explicit UML semantics.
What teams see in practice
D2 strengths
- Layout stays clean when diagrams grow, which is ideal for runbooks and incident docs.
- Diffs are easy to review because the syntax is compact.
- Default styling keeps diagrams consistent without much configuration.
PlantUML strengths
- UML coverage is deep, which matters for regulated or compliance-heavy documentation.
- Sequence diagrams are precise and stable across changes.
- Rendered output is consistent across environments when centralized in CI or a server.
Collaboration and workflow
| Workflow need | D2 | PlantUML |
|---|---|---|
| Git review readability | ✅ Friendly diffs | ⚠️ Can be verbose |
| Architecture governance | ✅ Great for system maps | ✅ Best for formal UML |
| Automation in CI | ✅ Lightweight rendering | ✅ Stable with server rendering |
| Legacy UML support | ⚠️ Limited | ✅ First-class |
Practical guidance
Pick D2 when
- You want low-friction diagrams for product and platform teams.
- You need system maps that stay readable without manual layout tweaks.
- You want architecture diagrams to live in PRs and stay easy to review.
Pick PlantUML when
- UML compliance is required for internal standards or auditors.
- You need deep control over sequence, component, or deployment diagrams.
- You want consistent rendering across large documentation sets.
Recommendation matrix
| Scenario | Recommended language |
|---|---|
| Rapid prototyping for product squads | D2 |
| Enterprise UML documentation | PlantUML |
| Multi-cloud architecture reviews | D2 |
| Formal sequence diagrams for QA | PlantUML |
| Collaborative editing with AI assistance | D2 via UniDiagram |
Final thoughts
D2 makes it easy to keep architecture maps current and readable, which is why it fits modern delivery teams. PlantUML remains indispensable for formal UML documentation where correctness and semantic detail matter. If your organization spans both needs, it is common to standardize on D2 for everyday diagrams and PlantUML for formal artifacts, with UniDiagram as the shared workspace.
If your problem is keeping diagrams consistent across teams or fighting with slow tooling, UniDiagram solves it with a better editor experience, live previews, and AI suggestions. It streamlines authoring so you can focus on communicating the system clearly.