Diagram Creator

Diagram Creator

Generate stunning, self-contained HTML diagrams with professional typography, smooth animations, and an infinite canvas you can pan and zoom like Miro. Output is always a single .html file that opens directly in any browser — zero dependencies. Supports 5 themes and 8 topology layouts.

Input Handling

Accept any of these inputs and auto-process them:

| Input type | How to handle | |---|---| | Topic/description | "Docker networking", "OAuth 2.0 flow" — use directly | | Markdown (.md, .mdx) | Extract structure from headings, lists, tables, relationships | | JSON / YAML (.json, .yaml, .yml, .jsonl) | Parse structure — keys become nodes, nesting becomes layers | | Code files (.py, .ts, .js, .go, .rs, .java, .rb, .php, .swift, .kt, .c, .cpp, .cs, .scala, etc.) | Extract classes, functions, imports, inheritance — diagram the architecture | | Config / Infra (.toml, .ini, .env, .tf, .hcl, Dockerfile, docker-compose.yml, Makefile, nginx.conf) | Map services, variables, dependencies, infrastructure | | API specs (.openapi.yaml, .swagger.json, .graphql, .proto) | Extract endpoints, types, service relationships | | Database schemas (.sql, .prisma, .dbml) | Map tables, columns, foreign keys, relationships | | CI/CD pipelines (.github/workflows/*.yml, .gitlab-ci.yml, Jenkinsfile) | Visualize pipeline stages and deployment flows | | Data files (.csv, .tsv) | Identify columns as entities, rows as relationships | | Microsoft Office (.xlsx, .xls, .docx, .doc, .pptx, .ppt) | Extract tables, headings, slide structure, org charts, SmartArt | | Package manifests (package.json, requirements.txt, Cargo.toml, go.mod, pom.xml) | Map dependency trees | | Existing diagrams (.drawio, .puml, .mermaid) | Read spec and re-render with this design system | | PDF / Docs (.pdf, .txt, .rst, .adoc) | Read content, extract core structure | | Notebooks (.ipynb) | Extract code cells, data flow, library dependencies |

If it's a file, this skill can diagram it. For formats not listed, read the content and extract whatever structure exists.

When receiving a file path, read the file, detect the extension, and intelligently extract what matters for the diagram. Don't ask the user to reformat — figure it out.

If the input is genuinely ambiguous (no clear structure to extract), ask clarifying questions before proceeding. See "Pre-generation Questions" below.

Pre-generation Questions

Always ask these questions before generating, unless the answer is completely obvious from the input. Ask one question at a time — wait for the user's answer before moving to the next. Present every question as a numbered list so the user can simply reply with a number.

Skip a question ONLY when the answer is unambiguous — e.g., "diagram of Docker bridge networking" makes topology (nested) and detail level (medium) obvious. When in doubt, ask.

Question flow (one at a time, in this order):

1. What to visualize? (skip only if input is already specific)

Present 2-3 interpretations of the input as numbered options, plus an "Other" option. Tailor the options to what the user actually asked — don't use generic placeholders. `` What do you want to visualize? 1) [interpretation A] 2) [interpretation B] 3) Other — describe below → Reply with the number: ``

1. Layout? (skip if only one topology realistically fits — choose automatically in Step 0)

Only list the 2-3 topologies that could realistically fit, not all 8. Adapt options based on the previous answer. `` Layout? 1) Left-to-right — sequential flow 2) Timeline — vertical step sequence → Reply with the number: ``

1. Detail level?

`` Detail level? 1) High-level — main entities only, understand in 5 seconds 2) Medium — entities with key info, labeled connections (default) 3) Detailed — full technical breakdown, all metadata → Reply with the number (default: 2): ``

1. Theme?

`` Theme? 1) Dark (default) 2) Light 3) Corporate 4) Neon 5) Minimal → Reply with the number (default: 1): ``

Once you have all the answers, proceed autonomously through all remaining steps without further questions.

Step 0 — Choose the Topology

Pick exactly one topology based on what fits the content best:

| Topology | When to use | Examples | |---|---|---| | nested | Hierarchical containment, layers wrapping layers | Docker networking, K8s pods, OSI model, VPC subnets | | left-to-right | Sequential flow from A to Z | OAuth flow, CI/CD pipeline, user journey, request lifecycle | | hub-and-spoke | Central node connected to N surrounding nodes | API gateway, microservices, load balancer, team structure | | timeline | Ordered vertical sequence of events/steps | Deploy pipeline, project roadmap, historical events | | grid | Matrix/table comparison, feature grids | Feature comparison, skill map, competitive landscape | | tree | Hierarchical branching, org charts | Org chart, file tree, decision tree, taxonomy | | funnel | Progressive narrowing, conversion stages | Sales funnel, data pipeline, filtering process | | comparison | Side-by-side 2-3 options | Product vs product, technology choices, before/after |

Step 1 — Plan the Content

Before writing HTML, plan these elements in your thinking:

• Topic: one sentence describing what the diagram shows
• Detail level: choose one of three levels. Default to medium unless context suggests otherwise:
• High-level — Only the main entities of the system. Aggregate similar entities into single boxes (e.g., "Backend Services" instead of listing 10 microservices). No metadata in boxes — just name and role. Minimal connection labels. No callouts, badges, or notes. The viewer should understand the structure in 5 seconds.
• Medium (default) — The entities needed to understand how the system works, without sub-components. Each box gets 1-2 metadata relevant to the domain (infra: port and protocol; org chart: role and team; flow: input/output of each step). Label connections where it adds clarity. Callouts only for non-obvious key concepts. The viewer who knows the domain should understand the diagram without further explanation.
• Detailed — Everything: sub-components, configurations, technical notes. All relevant metadata per box (ports, protocols, versions, env vars, states). Badges, explanatory callouts, side notes. Goal: complete technical reference for people working on the system.

How to choose: (1) If the user specifies a level explicitly, use it. (2) If context clarifies intent — a presentation implies high-level, a technical doc for the team implies detailed — match it. (3) Otherwise default to medium. (4) If the chosen level produces too many elements for the topology, aggregate entities into groups rather than changing level or topology.

• Layers/Steps: each level with name, description, and accent color. For left-to-right topology, count the steps and apply the step count scaling table from references/topology-layouts.md to set step max-width and arrow width accordingly
• Nodes: each box with emoji, name, and metadata density matching the detail level above
• Connections: what each arrow represents (label density matches detail level)
• Special Components: callout boxes, badges, info panels (reduce or skip for high-level)
• Legend Entries: one per accent color used

Step 1.5 — Choose the Theme

If the user specifies a theme, use it. Otherwise default to dark.

| Theme | Best for | Keywords | |---|---|---| | dark (default) | Technical diagrams, dev docs | "dark", default | | light | Presentations, documentation sites | "light", "chiaro", "presentation" | | corporate | Business plans, pitch decks | "corporate", "business", "professional" | | neon | Creative, gaming, social media | "neon", "cyberpunk", "vibrant" | | minimal | Clean docs, technical specs | "minimal", "clean", "simple" |

See references/themes.md for the exact :root values and overrides per theme.

Step 2 — Build the HTML

Read the reference files for detailed CSS/layout specifications:

• references/typography-and-colors.md — fonts, palette, background
• references/themes.md — theme system with 5 color schemes
• references/topology-layouts.md — layout rules for each of the 8 topologies
• references/components.md — node cards, badges, callouts, legend, animations
• references/safety-rules.md — mandatory layout constraints for all topologies
• references/canvas.md — infinite canvas with pan & zoom (Miro-like navigation)

Follow every rule in those references exactly. The design system is battle-tested — don't improvise fonts, colors, or layout patterns.

Always include the infinite canvas system from references/canvas.md. This lets users pan (click+drag) and zoom (scroll wheel) the diagram freely, like a whiteboard.

Step 3 — Output

• Single .html file, all CSS in `, all JS in `
• No external dependencies except Google Fonts via @import
• No CSS frameworks, no JS libraries (vanilla JS for hub-and-spoke coordinates and canvas pan/zoom)
• Valid HTML5 with `` as first line
• Must render correctly opened directly in a browser
• Responsive down to 360px viewport width

Save as diagram-[topic-slug].html in the current working directory. Open it in the browser with open (macOS) or xdg-open (Linux). Tell the user where it was saved.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: ferdinandobons
• Source: ferdinandobons/diagram-creator-skill
• License: MIT

Install and usage instructions live in the source repository linked above.