C4 Architecture Diagram Tool — All Four Zoom Levels, AI-Generated

The four C4 zoom levels

C4 (Context, Container, Component, Code) is a hierarchical model for describing software architecture at different levels of abstraction, developed by Simon Brown. Each level answers a specific audience's question — from executives ("what does this system do?") to developers ("which class handles authentication?").

flow-chart.io generates all four levels from a single description. The AI infers the correct abstraction boundaries at each zoom level, places named boxes with technology labels, and routes relationships with labeled arrows — following C4 notation conventions throughout.

What flow-chart.io generates for C4

• Level 1 Context diagrams — your system in relation to users and external systems
• Level 2 Container diagrams — the high-level technical building blocks (web app, API, database, message queue)
• Level 3 Component diagrams — the internal structure of a single container, down to components and interfaces
• Level 4 Code diagrams — class-level detail for the most critical components
• Correct C4 notation — person shapes for users, rounded rectangles for containers, labeled relationship arrows
• Technology labels on every box — e.g. "React SPA", "Node.js API", "PostgreSQL 15"

How to generate a C4 diagram

1. Sign up free — 5 diagrams, no credit card required.
2. Select the C4 model domain in the diagram type picker.
3. Describe your system — e.g. "E-commerce platform: customer, React SPA, Node API, Stripe, PostgreSQL, Redis cache, email service."
4. Choose the zoom level — Context, Container, Component, or Code — and edit the result.

Frequently asked questions

What is the C4 model?

The C4 model is a set of four hierarchical diagrams — Context, Container, Component, Code — that describe a software system at different levels of abstraction. Developed by Simon Brown, it's designed to be accessible to both technical and non-technical audiences.

Do I need to generate all four levels?

No. You can generate just the level you need. Most teams start with a Context diagram for stakeholder communication and a Container diagram for architecture review. Component and Code diagrams are optional for deep dives.

How does flow-chart.io handle technology labels?

The AI extracts technology names from your description and places them as sublabels on each box — exactly as C4 conventions specify. You can edit any label after generation.

Can I use C4 diagrams in architecture review documents?

Yes. Export as SVG or PNG and embed in Confluence, Notion, Google Docs, or any documentation system. The JSON export lets you reimport and update the diagram later.