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PlantUML

plantuml.com

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Spec score 8.5 #15 of 46 in Diagramming tools

What it is

PlantUML turns textual descriptions into diagrams, covering UML forms such as sequence, use-case, class, object, activity, component, deployment, state, and timing diagrams. It also supports JSON, YAML, EBNF, regex, network, wireframe, Archimate, Gantt, mind map, and WBS diagrams. Outputs include PNG, SVG, LaTeX, EPS, and other listed formats; sequence diagrams can also be rendered as ASCII art. Its browser editor renders diagrams with JavaScript and refreshes them as the text changes. Layout options include Graphviz, Smetana, VizJs, and ELK, though ELK lacks some features. PlantUML offers integrations for tools including GitHub, GitLab, Confluence, WordPress, Slack, Visual Studio Code, Eclipse, and IntelliJ IDEA. It is free, with a plan listed at free, and runs on web, Windows, macOS, Linux, API, extension, and self-hosted platforms. Local installation requires Java, with version 11 or later recommended; Graphviz is needed for some diagrams. PlantUML can also run as a local server, which the project recommends for sensitive diagrams.

Spec sheet

Purpose
PlantUML creates diagrams from simple textual descriptions.Read 7 Oct 2026 · plantuml.com
Free plan
YesRead 20 Sep 2026 · plantuml.com
Integrations
The project lists integrations with tools including GitHub, GitLab, Confluence, WordPress, Slack, Visual Studio Code, Eclipse, and IntelliJ IDEA.Read 7 Oct 2026 · plantuml.com
Support
The project directs users to its community forum for advice and solutions to common layout issues.Read 7 Oct 2026 · plantuml.com
Founded
2009Read 28 Sep 2026 · plantuml.com
Browser editor
The site’s editor runs in the browser using a JavaScript rendering engine and updates diagrams as code is edited.Read 7 Oct 2026 · plantuml.com
Browser extension
The official browser extension renders PlantUML diagrams directly inside GitHub without a server, and the site says it uses no tokens or tracking and requests no permissions except clipboard.Read 7 Oct 2026 · plantuml.com
Diagram size
The FAQ states that image width and height are limited to 4096 by default, with an environment variable or command-line option to change the limit.Read 7 Oct 2026 · plantuml.com
Diagram types
It supports UML diagrams including sequence, use case, class, object, activity, component, deployment, state, and timing diagrams.Read 7 Oct 2026 · plantuml.com
Layout engines
Available layout engines include Graphviz, Smetana, VizJs, and ELK; ELK supports orthogonal layout and does not cover all features.Read 7 Oct 2026 · plantuml.com
Local requirements
Local installation requires Java, with Java 11 or later recommended; Graphviz is needed only for some diagrams.Read 7 Oct 2026 · plantuml.com
Notable limitation
PlantUML functions as a drawing generator rather than a modeling tool and does not prevent inconsistent diagrams.Read 7 Oct 2026 · plantuml.com
Other diagrams
Supported non-UML diagrams include JSON, YAML, EBNF, regex, network, wireframe, Archimate, Gantt, mind map, and WBS diagrams.Read 7 Oct 2026 · plantuml.com
Outputs
Diagram output formats include PNG, SVG, LaTeX, EPS, and ASCII art for sequence diagrams.Read 7 Oct 2026 · plantuml.com
Security profiles
PlantUML provides security profiles that control access to local files and URLs, including INTERNET, ALLOWLIST, and SANDBOX modes.Read 7 Oct 2026 · plantuml.com
Self hosting
PlantUML can run as a local server, and the project recommends this for generating diagrams that contain sensitive information.Read 7 Oct 2026 · plantuml.com
Server privacy
The FAQ says PlantUML Server does not store diagrams, but warns that traffic goes through HTTP and can be intercepted.Read 7 Oct 2026 · plantuml.com

Plans and prices

PlantUML Free Open source · Free of charge · Available under several licenses, with some features varying by license Read 7 Oct 2026 · plantuml.com

Every PlantUML plan and price →

Strong points and limits

Strong points

  • Creates diagrams from textual descriptions.
  • Supports UML and many non-UML diagram types.
  • Browser editor updates diagrams as code changes.
  • Offers multiple output formats and layout engines.
  • Can run locally or as a self-hosted server.

Limits

  • Local installation requires Java.
  • Graphviz is needed for some diagrams.
  • It does not prevent inconsistent diagrams.
  • ELK does not cover every feature.

Who it suits

PlantUML suits people who want to generate diagrams from text, including UML and several non-UML formats. It also fits teams that want browser editing, integrations, or local hosting for sensitive diagrams.

Verdict

PlantUML offers broad diagram coverage and several ways to render and integrate diagrams. It is a drawing generator rather than a modeling tool, so it does not check diagrams for consistency.

Where Specifiction places it

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