Architecture Diagram

Back to Style Guide — Read the style guide first for emoji, color, and accessibility rules.

Syntax keyword: architecture-beta Best for: Cloud infrastructure, service topology, deployment architecture, network layout When NOT to use: Logical system boundaries (use C4), component layout without cloud semantics (use Block)

⚠️ Accessibility: Architecture diagrams do not support accTitle/accDescr. Always place a descriptive italic Markdown paragraph directly above the code block.

Exemplar Diagram

Architecture diagram showing a cloud-hosted web application with a load balancer, API server, database, and cache deployed within a VPC:

mermaid

architecture-beta
    group cloud(cloud)[AWS Cloud]
    group vpc(cloud)[VPC] in cloud

    service lb(internet)[Load Balancer] in vpc
    service api(server)[API Server] in vpc
    service db(database)[PostgreSQL] in vpc
    service cache(disk)[Redis Cache] in vpc

    lb:R --> L:api
    api:R --> L:db
    api:B --> T:cache

Tips

Use group for logical boundaries (VPC, region, cluster, availability zone)
Use service for individual components
Direction annotations on connections: :L (left), :R (right), :T (top), :B (bottom)
Built-in icon types: cloud, server, database, internet, disk
Nest groups with in parent_group
Labels must be plain text — no emoji and no hyphens in [] labels (parser treats - as an edge operator)
Use --> for directional arrows, -- for undirected edges
Keep to 6–8 services per diagram
Always pair with a Markdown text description above for screen readers

Template

Description of the infrastructure topology and key components:

mermaid

architecture-beta
    group region(cloud)[Cloud Region]

    service frontend(internet)[Web Frontend] in region
    service backend(server)[API Server] in region
    service datastore(database)[Database] in region

    frontend:R --> L:backend
    backend:R --> L:datastore

Complex Example

Multi-region cloud deployment with 3 nested groups (2 regional clusters + shared services) showing 9 services, cross-region database replication, CDN distribution, and centralized monitoring. Demonstrates how nested group + in syntax creates clear infrastructure boundaries:

mermaid

architecture-beta
    group cloud(cloud)[AWS Platform]

    group east(cloud)[US East Region] in cloud
    service lb_east(internet)[Load Balancer East] in east
    service app_east(server)[App Server East] in east
    service db_primary(database)[Primary Database] in east

    group west(cloud)[US West Region] in cloud
    service lb_west(internet)[Load Balancer West] in west
    service app_west(server)[App Server West] in west
    service db_replica(database)[Replica Database] in west

    group shared(cloud)[Shared Services] in cloud
    service cdn(internet)[CDN Edge] in shared
    service monitor(server)[Monitoring] in shared
    service queue(server)[Message Queue] in shared

    cdn:B --> T:lb_east
    cdn:B --> T:lb_west
    lb_east:R --> L:app_east
    lb_west:R --> L:app_west
    app_east:B --> T:db_primary
    app_west:B --> T:db_replica
    db_primary:R --> L:db_replica
    app_east:R --> L:queue
    app_west:R --> L:queue
    monitor:B --> T:app_east

Why this works

Nested groups mirror real infrastructure — cloud > region > services is exactly how teams think about multi-region deployments. The nesting creates clear blast radius boundaries.
Plain text labels only — architecture diagrams parse-fail with emoji in [] labels. All visual distinction comes from the group nesting and icon types (internet, server, database).
Directional annotations prevent overlap — :B --> T: (bottom-to-top), :R --> L: (right-to-left) control where edges connect. Without these, Mermaid stacks edges on top of each other.
Cross-region replication is explicit — the db_primary:R --> L:db_replica edge is the most important infrastructure detail and reads clearly as a horizontal connection between regions.