ClaudSkills / Engineering / architecture

C4 Model

Q: What is a Claude Code skill and how does the C4 Model skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. C4 Model is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Engineering · Sub-category: architecture · Last updated: 2026-08-20

tool:gitlab type:review

Create or review C4 model architecture documentation (official c4model.com notation) as diagrams-as-code in Markdown — C4-PlantUML where the target renders it (GitLab.com does; verify Self-Managed instances), Mermaid flowchart/sequence conventions otherwise. Use whenever the user wants to visualize or document the architecture of a system or codebase — even if they never say "C4" — for requests like "diagram this service", "document the architecture", "how do the pieces of this repo fit together", "draw the system/containers/components", or when reviewing existing C4/Mermaid architecture diagrams for correctness. Covers system context, system landscape, container, component, dynamic, and deployment views. Do not use for generic flowcharts, ER diagrams, standalone Kubernetes topology, API contract documentation (OpenAPI/AsyncAPI), or architecture prose without diagrams.

Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

Generate C4 model architecture documentation as diagrams-as-code embedded in Markdown — in the selected notation — following the official guidance at c4model.com. The point of C4 is a small set of precise abstractions and views that stay consistent with each other — most of this skill exists to protect that precision.

What this skill does

C4 Model is a community-contributed Claude Code skill in the architecture sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/c4-model/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use whenever the user wants to visualize or document the architecture of a system or codebase — even if they never say "C4" — for requests like "diagram this service", "document the architecture", "how do the pieces of this repo fit together", "draw the system/containers/components", or when reviewing existing C4/Mermaid architecture diagrams for correctness. Covers system context, system landscape, container, component, dynamic, and deployment views.

Who uses this skill

The C4 Model Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 191,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/c4-model
curl -L https://claudskills.com/skills/c4-model/SKILL.md \
  -o ~/.claude/skills/c4-model/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/c4-model/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/c4-model/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\c4-model\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the C4 Model Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/c4-model/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the C4 Model skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the C4 Model skill?

Use C4 Model when your Claude Code task falls under the Engineering category — specifically in the architecture area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use C4 Model" or describe the task and let Claude pick). Browse related skills at /category/engineering/.

What is a Claude Code skill and how does the C4 Model skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. C4 Model is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Source: https://github.com/mryll/skills/blob/HEAD/skills/c4-model/SKILL.md
License: MIT
Author: mryll

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

mryll. (2026). C4 Model [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/c4-model/

BibTeX

@misc{c4-model-2026,
  author    = {mryll},
  title     = {C4 Model [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/c4-model/}
}

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Security scan

Grade A · scanned 2026-08-25 — free static scan against the OWASP Agentic Skills Top 10.

No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›

✓ Prompt injection
✓ Data exfiltration
✓ Supply chain
✓ Reverse shell
✓ Credentials
✓ Execution
✓ Filesystem
✓ Persistence
✓ Obfuscation
✓ Network

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[![Security: A](https://img.shields.io/badge/Security-A-2e7d32)](https://claudskills.com/skills/c4-model/#security)

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Part of ClaudSkills — the open registry for Claude Skills & Claude Code Skills. · What's New · Install guide · About · llms.txt

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