PlantUML ASCII

PlantUML ASCII is an instruction skill published by GitHub in the official github/awesome-copilot repository. Its primary source is the skills/plantuml-ascii directory, which explains how a Copilot or another compatible agent can turn PlantUML text diagrams into readable output for terminals, READMEs, email, and text-oriented documentation. According to the provider, the template is intended for cases where an image is unavailable, undesirable, or difficult to version. The skill is therefore not an independent diagram renderer and not a hosted service. It is a reproducible body of guidance that helps an agent operate an existing local PlantUML installation.

Workflow and diagram types

The instructions start with a PlantUML source file enclosed by the startuml and enduml markers. From that source, users can produce sequence diagrams with actors and participants, class diagrams with fields and methods, activity diagrams with decisions, state diagrams, component views, use case diagrams, and deployment diagrams. The source distinguishes txt for plain ASCII output from utxt for a Unicode-enhanced variant using box-drawing and connector characters. This distinction matters in practice. Plain ASCII is dependable in older terminals and simple log systems, while Unicode can improve visual structure when the target environment has reliable UTF-8 support and a suitable font.

Practical value

The skill is useful for architecture notes in pull requests, technical sketches at a console, documentation kept next to commits, and messages that cannot carry embedded images. An agent can turn a user’s system description into a diagram with short labels and then suggest an output mode appropriate for the destination. The primary source stresses that fixed-width rendering is important because long labels can damage alignment and readability. Complex diagrams should also be checked in the exact environment where they will be shared. For very large or highly visual designs, Mermaid, Graphviz, or graphical PlantUML output may remain a better choice.

Requirements and boundaries

Execution requires PlantUML on the selected system, or an available Java-based PlantUML runtime. The skill does not install that tool and does not contain its parser or rendering implementation. It only documents the workflow and relevant options. The MIT license recorded here refers to the PlantUML ASCII skill file in the GitHub repository; users must separately review the license terms for their installed PlantUML version and any other dependencies. The figure of 38,791 GitHub stars was retrieved on September 9, 2026 through the official GitHub API for the entire github/awesome-copilot repository. It is a time-bound repository popularity signal, not evidence of quality, security, or isolated adoption of this subdirectory.

Security and responsibility

The template works with local diagram files and, depending on the selected agent, may guide writes to output directories. Review paths, inputs, and generated files before automated follow-up processing. PlantUML text can originate from untrusted sources and should be checked like any other input for unwanted content. According to the provider, the skill documents output formats and common workflows but does not guarantee a specific PlantUML version or perfect rendering for every diagram. A connected model may also transmit data to its model provider, so local text rendering should not be confused with complete data locality for the entire agent workflow.