LikeC4: The Open-Source Tool That Turns Your Code Into Living Architecture Diagrams — 5,100+ GitHub Stars

Why Architecture Documentation Keeps Going Stale (And How LikeC4 Fixes It)

Every developer has been there: you join a new team, ask for architecture documentation, and get handed a diagram from 2019 that bears zero resemblance to the current codebase. The microservices have multiplied. The message queues have migrated. The "simple three-tier architecture" is now a distributed mesh that would make a senior engineer weep.

The problem isn't laziness—it's friction. Manually updating diagrams is tedious, error-prone, and always one commit behind. By the time you finish drawing, the code has already changed.

LikeC4 solves this by flipping the model: instead of drawing diagrams and hoping they stay current, you describe your architecture in code, and LikeC4 generates the diagrams for you. Every. Single. Time.

What is LikeC4?

LikeC4 is an open-source modeling language and toolkit for software architecture visualization. It's inspired by two well-established approaches:

• C4 Model — Simon Brown's hierarchical method for visualizing software architecture at different levels of abstraction (Context, Containers, Components, Code)
• Structurizr DSL — A domain-specific language for describing software architecture as code

But LikeC4 doesn't stop at copying these predecessors. It adds flexibility: you can customize notation, define your own element types, and create any number of nested levels. It's C4 Model with the guardrails removed—perfectly tailored to your team's needs.

Written in TypeScript and MIT-licensed, LikeC4 runs as a CLI tool, a VSCode extension, and a web-based playground. You write your architecture in a simple DSL, run a command, and get interactive, zoomable diagrams that live in your browser.

How LikeC4 Works: From Code to Diagram in 60 Seconds

Here's the basic workflow:

1. Describe Your Architecture

Create a .c4 file (or multiple files) that describes your system. The syntax is clean and readable:

specification {
  element person
  element system
  element component
  element database
  
  relationship uses
  relationship reads
  relationship writes
}

model {
  customer = person "Customer" {
    description "A user of the banking app"
  }
  
  banking = system "Banking System" {
    webapp = component "Web Application" {
      technology "React + Node.js"
    }
    
    api = component "API Gateway" {
      technology "Express.js"
    }
    
    db = database "PostgreSQL" {
      technology "PostgreSQL 15"
    }
    
    webapp -> api "makes API calls"
    api -> db "reads/writes data"
  }
  
  customer -> webapp "uses"
}

views {
  view index {
    title "Banking System - Overview"
    include *
  }
}

2. Generate the Diagram

Run the CLI:

npx likec4 start

LikeC4 parses your model, applies auto-layout algorithms, and serves an interactive web interface at localhost:3000. You can zoom, pan, click elements to drill down, and export to PNG, SVG, or PDF.

3. Keep It in Sync

Because your architecture lives in code (right next to your application code), it gets updated in the same pull requests. When a developer adds a new microservice, they update the .c4 file. The diagram regenerates automatically. No more "we'll update the docs later" lies.

Key Features That Set LikeC4 Apart

Custom Notation and Element Types

Unlike rigid C4 Model implementations, LikeC4 lets you define your own vocabulary. Need a "message queue" element type? A "serverless function" type? A "third-party API" type? Define it once, use it everywhere.

specification {
  element queue {
    style {
      color #FF6B6B
      shape queue
    }
  }
  
  element serverless {
    style {
      color #4ECDC4
      shape hexagon
    }
  }
}

Nested Levels of Abstraction

C4 Model traditionally has four levels. LikeC4 removes that limit. You can nest systems within systems, drilling down from high-level context to individual classes if you want. Most teams stop at 3-4 levels, but the option is there.

Live Preview and Collaboration

The web interface isn't just a static image. It's a fully interactive explorer:

• Click any element to see its relationships and metadata
• Toggle visibility of specific element types
• Filter views by tags or technologies
• Share a URL with teammates—they see the same diagram

VSCode Integration

The LikeC4 VSCode extension provides:

• Syntax highlighting for .c4 files
• Real-time preview as you type
• Go-to-definition for element references
• Linting and validation

Export and Embed

Export diagrams as:

• PNG for presentations
• SVG for documentation sites
• PDF for printed reports
• Embeddable iframes for internal wikis

Real-World Example: Documenting a Microservices E-Commerce Platform

Let's say you're building an e-commerce platform with 12 microservices, 3 databases, 2 message queues, and external integrations with Stripe, SendGrid, and a legacy ERP system.

Without LikeC4: You create a Lucidchart diagram. It takes 4 hours. Two weeks later, someone adds a Redis cache layer. The diagram is now wrong. Nobody updates it. Six months later, a new engineer joins and spends three days figuring out how the order service talks to the inventory service.

With LikeC4:

model {
  ecommerce = system "E-Commerce Platform" {
    
    frontend = component "Web Frontend" {
      technology "Next.js"
    }
    
    orders = component "Order Service" {
      technology "Go + gRPC"
    }
    
    inventory = component "Inventory Service" {
      technology "Node.js + Express"
    }
    
    payments = component "Payment Service" {
      technology "Python + FastAPI"
    }
    
    ordersDB = database "Orders DB" {
      technology "PostgreSQL"
    }
    
    inventoryDB = database "Inventory DB" {
      technology "MongoDB"
    }
    
    events = queue "Event Bus" {
      technology "RabbitMQ"
    }
    
    cache = component "Redis Cache" {
      technology "Redis 7"
    }
    
    frontend -> orders "places orders"
    frontend -> inventory "checks stock"
    
    orders -> ordersDB "persists orders"
    orders -> events "publishes OrderCreated"
    orders -> payments "initiates payment"
    
    inventory -> inventoryDB "tracks stock"
    inventory -> events "publishes StockUpdated"
    inventory -> cache "caches hot items"
    
    events -> orders "consumes PaymentCompleted"
    events -> inventory "consumes OrderCreated"
  }
  
  stripe = system "Stripe" {
    description "Payment processor"
  }
  
  payments -> stripe "charges customers"
}

Run npx likec4 start, and you get an interactive diagram showing all services, their relationships, and technologies. Click on "Order Service" to see exactly what it talks to. Filter by "database" to see your data layer. Export to SVG and embed it in your README.

Total time: 20 minutes to write, 0 minutes to maintain (it's version-controlled with your code).

Key Benefits of Using LikeC4

• Always up-to-date: Diagrams regenerate from code—no manual updates, no drift
• Version-controlled: Architecture lives in Git, so you can diff, branch, and review changes
• Customizable: Define your own notation, colors, shapes, and element types
• Interactive: Web-based explorer lets you drill down, filter, and share
• Fast onboarding: New team members understand the system in minutes, not days
• CI/CD friendly: Generate diagrams in your pipeline, publish to your docs site automatically
• Free and open-source: MIT license, no vendor lock-in, self-hostable

Frequently Asked Questions

1. Is LikeC4 free to use?

Yes, LikeC4 is 100% free and open-source under the MIT license. You can use it for personal projects, commercial applications, or internal tools without any restrictions or licensing fees.

2. Do I need to know the C4 Model to use LikeC4?

No. While LikeC4 is inspired by the C4 Model, you don't need to follow it strictly. You can use C4's hierarchical approach, create your own levels of abstraction, or mix and match. The tool is flexible enough to adapt to your team's preferred methodology.

3. Can I use LikeC4 with existing documentation tools?

Absolutely. LikeC4 exports to PNG, SVG, and PDF, which you can embed in Notion, Confluence, GitHub wikis, or any documentation platform. You can also use the embeddable iframe to show live, interactive diagrams directly in your docs site.

4. How does LikeC4 handle large, complex systems?

LikeC4 uses automatic layout algorithms that scale well to large systems. For very complex architectures (50+ services), you can use tags and filters to show only relevant subsets. The nested abstraction levels also help—start with a high-level view and drill down as needed.

5. Can multiple people collaborate on the same architecture model?

Yes. Because LikeC4 models are just text files, they work perfectly with Git. Multiple developers can edit different .c4 files, merge changes via pull requests, and review architecture changes just like code changes. The web interface also supports sharing via URL for real-time collaboration.

6. Does LikeC4 integrate with CI/CD pipelines?

Yes. You can run LikeC4 in your CI/CD pipeline to automatically generate and publish diagrams whenever your architecture changes. Many teams add it to their documentation build process, so diagrams are always current on their internal wiki or public docs site.

7. What's the difference between LikeC4 and tools like Lucidchart or Draw.io?

Lucidchart and Draw.io are manual drawing tools—you create diagrams by dragging and dropping shapes. LikeC4 is a code-first tool—you describe your architecture in a DSL, and diagrams are generated automatically. This means LikeC4 diagrams never go stale (they're tied to your code), while manual diagrams require constant maintenance.