Serverless API Project
Part of the Cloud Computing Roadmap
In short
A serverless API costs almost nothing when nobody calls it and scales when your post goes viral. Building one proves you can design with managed pieces instead of servers.
Build a real API entirely on serverless components — API Gateway, functions, and a serverless database — showing you can design and deploy an event-driven, fully managed architecture.
Think of it like this
The chemist's night bell
The night chemist doesn't sit at the counter all night. When someone rings the bell, he wakes, hands over the medicine, notes it in his register and goes back to sleep. You only pay him for the times the bell rang.
Watch it happen
POST /notes on a fully managed stack
POST /notes
1/6The client sends JSON. API Gateway checks the route and, if you set it up, the auth token.
The big ideas
What you need to know
Routes, functions, table
Must-haves: CRUD routes in API Gateway, one function per route or a small router, and a DynamoDB table.
Auth and least privilege
Protect write routes with a JWT authorizer, such as Cognito. Give each function access to only what it needs.
Deploy as code
Use AWS SAM, Serverless Framework, CDK or Terraform. Clicking in the console isn't repeatable.
Logs and limits
Show CloudWatch logs, set throttling on the API, and explain cold starts in your README.
See it in code
Walk through the code
1import { DynamoDBClient } from "@aws-sdk/client-dynamodb";2import { DynamoDBDocumentClient, PutCommand } from "@aws-sdk/lib-dynamodb";3import { randomUUID } from "node:crypto";4import type { APIGatewayProxyHandlerV2 } from "aws-lambda";5 6const db = DynamoDBDocumentClient.from(new DynamoDBClient({}));7 8export const handler: APIGatewayProxyHandlerV2 = async (event) => {9 const body = JSON.parse(event.body ?? "{}");10 if (!body.title) return { statusCode: 400, body: "title is required" };11 const note = { id: randomUUID(), title: body.title, createdAt: Date.now() };12 await db.send(new PutCommand({ TableName: process.env.TABLE_NAME, Item: note }));13 return { statusCode: 201, body: JSON.stringify(note) };14};1/4Create the client outside the handler, so warm invocations reuse the connection.
The create-note function on Node.js. The table name comes from an environment variable set by your deploy tool.
Save yourself the pain
Common mistakes
Oops
Giving the function an IAM policy with dynamodb:* on all tables.
Do this instead
Allow only the actions it uses, like PutItem and GetItem, on that one table's ARN.
Oops
Designing DynamoDB tables like SQL tables and scanning for every query.
Do this instead
Plan the access patterns first, then pick keys. Scans read the whole table and get slow and costly.
Your mission
First milestone: one live route
Quick check
Why is the DynamoDB client created outside the handler function?
Go deeper
- 1Design an API with at least 3-4 distinct endpoints and a clear data model.
- 2Wire together API Gateway, a function per endpoint, and a serverless database.
- 3Document your cost model — how the pay-per-use pricing works for this specific project.
More projects at this stop
Deploy a 3-Tier Web Application on AWS / Azure / GCP
Infrastructure as Code Project (Multi-Environment)
Highly Available Architecture Project
Cost-Optimized Migration Case Study
Monitoring & Alerting Setup Project
Portfolio Website or GitHub Showcase
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