Create interactive C4 model diagrams online. Visualize your software architecture at every level -- from system context to code -- with AI-powered discovery and real-time collaboration.
The C4 model is a lean, hierarchical approach to software architecture visualization created by Simon Brown. It describes software architecture at four levels of abstraction -- Context, Containers, Components, and Code -- making it easy for both technical and non-technical stakeholders to understand your system.
L1System ContextL2ContainerL3ComponentL4Code
Aurora Commerce
Browses and buysCharges cardsSends receipts
Customer
PERSON
Browses the catalogue and places orders.
Aurora Commerce
SYSTEM
The online store: catalogue, cart, checkout.
Stripe
EXTERNAL
Card payments.
Email provider
EXTERNAL
Order receipts.
Pick a level, or let it play.
The four levels, one by oneThe four levels, one by one
L1
The big picture
System Context (Level 1)
The highest level of abstraction. Shows your software system as a single box surrounded by the users and other systems it interacts with. Perfect for communicating scope and boundaries to non-technical stakeholders.
Bird's-eye view of your system landscape
Show users, actors, and external systems
Define system boundaries and interactions
Ideal for stakeholder presentations
L1System ContextL2ContainerL3ComponentL4Code
Aurora Commerce
Browses and buysCharges cardsSends receipts
Customer
PERSON
Browses the catalogue and places orders.
Aurora Commerce
SYSTEM
The online store: catalogue, cart, checkout.
Stripe
EXTERNAL
Card payments.
Email provider
EXTERNAL
Order receipts.
L2
Technical building blocks
Container Diagram (Level 2)
Zoom into a single system to reveal the high-level technical building blocks: web applications, APIs, databases, message queues, and file systems. Each container is a separately deployable unit that runs code or stores data.
Web apps, APIs, databases, and queues
Technology stack per container
Communication protocols and ports
Deployment-ready overview
L1System ContextL2ContainerL3ComponentL4Code
Aurora Commerce › Containers
Aurora Commerce
HTTPSREST/JSONSQLOrderPlacedCharges
Customer
PERSON
Web App
WEB · React
Checkout API
API · Go
Event bus
QUEUE · Kafka
Orders DB
DATABASE · Postgres
Stripe
EXTERNAL
L3
Inside each container
Component Diagram (Level 3)
Decompose each container into its major structural components -- services, controllers, repositories, and modules. This level bridges the gap between architecture and code, showing how responsibilities are organized.
Services, controllers, and repositories
Internal responsibility mapping
Interface and dependency visualization
Bridge between architecture and code
L1System ContextL2ContainerL3ComponentL4Code
Checkout API › Components
Checkout API
places orderpersistsauthorisesSQLHTTPS
CheckoutController
COMPONENT
OrderService
COMPONENT
OrderRepository
COMPONENT
PaymentGateway
COMPONENT
Orders DB
DATABASE
Stripe
EXTERNAL
L4
Implementation details
Code Level (Level 4)
The most detailed level maps directly to your source code. Track individual classes, functions, and files alongside their architectural role. Archyl links code elements to your repository so documentation stays connected to reality.
Classes, functions, and files
Linked to your Git repository
Drift detection against real code
Auto-discovered by AI analysis
L1System ContextL2ContainerL3ComponentL4Code
OrderService › Code
OrderService
«class»OrderService
- repo: OrderRepository
- payments: PaymentGateway
+ PlaceOrder(cart) (Order, error)
+ Cancel(id) error
«entity»Order
+ ID: uuid
+ Items: []LineItem
+ Total: Money
+ Status: OrderStatus
«interface»OrderRepository
+ Save(ctx, order) error
+ ByID(ctx, id) (Order, error)
«interface»PaymentGateway
+ Authorise(amount) error
Why Archyl
More than just a C4 diagram toolMore than just a C4 diagram tool
Archyl goes beyond static diagrams. AI discovery, drift detection, and Architecture as Code keep your documentation alive.
Everything you need to know about the C4 model and Archyl.
What is the C4 model for software architecture?
The C4 model is a hierarchical approach to visualizing software architecture created by Simon Brown. It uses four levels of abstraction -- Context, Containers, Components, and Code -- to describe a system from the broadest overview down to implementation details. It is technology-agnostic and works for any software system.
How is Archyl different from Structurizr or IcePanel?
Archyl combines C4 model visualization with AI-powered architecture discovery, drift detection, Architecture as Code (YAML DSL), MCP server integration, and architecture change request workflows. Unlike static diagramming tools, Archyl keeps your documentation connected to your actual codebase.
Can I create C4 diagrams for free?
Yes. Archyl offers a free Developer plan that lets you create C4 model diagrams, use AI discovery, and manage architecture documentation. No credit card required.
Does Archyl support Architecture as Code?
Yes. You can declare your entire C4 model in a single archyl.yaml file, version it in Git, and sync it from CI/CD pipelines via GitHub Actions, GitLab CI, or the REST API.
What is architecture drift detection?
Architecture drift detection measures how accurately your documented C4 model matches your actual codebase. Archyl computes a 0-100% health score by checking file paths, directory structure, and element existence -- fully deterministic, no AI involved in scoring.
Can AI agents use my C4 model?
Yes. Archyl provides a built-in MCP server that lets AI coding agents like Claude Desktop, Cursor, and VS Code Copilot query your architecture, read ADRs, and create or update elements through natural conversation.
Storefront
Checkout API
Customer
Payments
Orders DB
Event bus
Free plan forever
Ready to visualize your architecture?Ready to visualize your architecture?
Start creating interactive C4 model diagrams for free. No credit card required.
C4 model tool: generate your C4 diagrams from code
Create interactive C4 model diagrams online. Visualize software architecture at 4 levels: Context, Containers, Components, and Code.
The best C4 model tool for modern software teams
Create interactive C4 model diagrams online. Visualize your software architecture at every level -- from system context to code -- with AI-powered discovery and real-time collaboration.
See All Features
What is the C4 model?
The C4 model is a lean, hierarchical approach to software architecture visualization created by Simon Brown. It describes software architecture at four levels of abstraction -- Context, Containers, Components, and Code -- making it easy for both technical and non-technical stakeholders to understand your system.
System Context (Level 1)
The highest level of abstraction. Shows your software system as a single box surrounded by the users and other systems it interacts with. Perfect for communicating scope and boundaries to non-technical stakeholders.
Bird's-eye view of your system landscape
Show users, actors, and external systems
Define system boundaries and interactions
Ideal for stakeholder presentations
Container Diagram (Level 2)
Technical building blocks
Zoom into a single system to reveal the high-level technical building blocks: web applications, APIs, databases, message queues, and file systems. Each container is a separately deployable unit that runs code or stores data.
Web apps, APIs, databases, and queues
Technology stack per container
Communication protocols and ports
Deployment-ready overview
Component Diagram (Level 3)
Inside each container
Decompose each container into its major structural components -- services, controllers, repositories, and modules. This level bridges the gap between architecture and code, showing how responsibilities are organized.
Services, controllers, and repositories
Internal responsibility mapping
Interface and dependency visualization
Bridge between architecture and code
Code Level (Level 4)
Implementation details
The most detailed level maps directly to your source code. Track individual classes, functions, and files alongside their architectural role. Archyl links code elements to your repository so documentation stays connected to reality.