Architecture
A serverless API backend architecture diagram with API Gateway, Lambda authorizer functions, business logic functions, and managed cloud services including DynamoDB, S3, SQS, and SNS for a fully managed, auto-scaling backend. This template models the serverless-first approach where infrastructure management is eliminated entirely, with pay-per-invocation pricing and automatic scaling to zero. Essential for startups and teams building cost-efficient, event-driven API backends.
Full FlowZap Code
Client { # Client Application
n1: circle label:"API Request"
n2: rectangle label:"API Gateway (AWS/Azure)"
n3: rectangle label:"Receive Response"
n4: circle label:"End"
n1.handle(right) -> n2.handle(left)
n2.handle(bottom) -> Functions.n5.handle(top) [label="Invoke Lambda"]
n3.handle(right) -> n4.handle(left)
}
Functions { # Serverless Functions
n5: rectangle label:"Auth Authorizer Lambda"
n6: diamond label:"Token Valid?"
n7: rectangle label:"Business Logic Lambda"
n8: rectangle label:"Return 401"
n9: rectangle label:"Data Validation Lambda"
n10: rectangle label:"Response Formatter"
n5.handle(right) -> n6.handle(left)
n6.handle(right) -> n7.handle(left) [label="Authorized"]
n6.handle(bottom) -> n8.handle(top) [label="Denied"]
n7.handle(right) -> n9.handle(left) [label="Process"]
n9.handle(right) -> n10.handle(left) [label="Validated"]
n8.handle(top) -> Client.n3.handle(bottom) [label="401"]
n10.handle(top) -> Client.n3.handle(bottom) [label="200 JSON"]
n7.handle(bottom) -> ManagedServices.n11.handle(top) [label="Read/Write"]
}
ManagedServices { # Managed Cloud Services
n11: rectangle label:"DynamoDB / CosmosDB"
n12: rectangle label:"S3 Object Storage"
n13: rectangle label:"SQS Message Queue"
n14: rectangle label:"SNS Notification"
n15: rectangle label:"CloudWatch Logs"
n11.handle(right) -> n12.handle(left) [label="Store Assets"]
n13.handle(right) -> n14.handle(left) [label="Trigger"]
n14.handle(top) -> Functions.n7.handle(bottom) [label="Async Invoke"]
n15.handle(top) -> Functions.n10.handle(bottom) [label="Log"]
}
Why This Workflow?
Provisioning and managing servers for API backends is expensive and wasteful—most APIs have variable traffic with long idle periods. A serverless API backend eliminates infrastructure management entirely, with automatic scaling from zero to thousands of concurrent requests and pay-per-invocation pricing.
How It Works
- Step 1: Client requests arrive at the API Gateway which handles routing and throttling.
- Step 2: A Lambda authorizer validates JWT tokens before the request reaches business logic.
- Step 3: Business logic Lambda functions process the request and interact with managed services.
- Step 4: DynamoDB provides single-digit millisecond reads/writes without capacity planning.
- Step 5: SQS and SNS handle asynchronous processing and notifications.
- Step 6: CloudWatch provides logging and monitoring for all Lambda invocations.
Alternatives
Container-based backends (ECS/Fargate) offer more control but require capacity planning. Traditional servers provide predictable performance but waste resources during idle periods. This template shows the fully serverless approach for maximum cost efficiency.
Key Facts
| Template Name | Serverless API Backend Architecture |
| Category | Architecture |
| Steps | 6 workflow steps |
| Format | FlowZap Code (.fz file) |
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