Reference

AWS

One page per AWS service, updated as I actually use it in real projects. Reference notes, not tutorials, no fixed order.

AWS Amplify

The frontend library that handles Cognito token storage, silent refresh, and request signing so the app doesn't build that logic by hand.

Updated Aug 29, 2026

Amazon API Gateway

A fully managed REST API service: API types, caching, backend targets beyond Lambda, and authorizing directly against Cognito without a custom Lambda.

Updated Aug 29, 2026

Amazon CloudFront

CDN, reverse proxy, and WAF attachment point at once, the caching cost rule, and the signed URL TTL mismatch that quietly extends access.

Updated Aug 29, 2026

Amazon CloudWatch

Centralized logging and metrics, on-premises collection, custom metrics and alarms that trigger automated responses, and log analysis.

Updated Aug 29, 2026

Amazon Cognito

Managed user pools, custom OTP auth challenges, and the token lifecycle, notes from building passwordless auth for a real registration flow.

Updated Aug 29, 2026

Amazon DynamoDB

Single-table design, prefixed keys, inverted indexes, GSI overloading, sparse indexes, filter expressions vs indexes, streams, capacity modes, conditional writes, and TTL, all in one place.

Updated Aug 29, 2026

Amazon EventBridge

Managed event bus with content-based routing, how it differs from SNS, and connecting it directly to API Gateway without a transport Lambda.

Updated Aug 29, 2026

AWS IAM

Users vs roles and credentials, trust and permission policies, STS, identity-based vs resource-based policies, SCPs, policy evaluation order, and identity federation, all in one place.

Updated Aug 29, 2026

AWS Lambda

What it is, common event sources, the execution environment and cold start model, reserved concurrency, and the anti-patterns and guarantees to design around.

Updated Aug 29, 2026

Amazon S3

Static hosting that scales on its own, and why a private bucket behind CloudFront beats a public one for user-specific files.

Updated Aug 29, 2026

Amazon SNS

Managed SMS delivery, used for OTP codes and failure notifications, and how it differs from EventBridge.

Updated Aug 29, 2026

Amazon SQS

Durable message queue mechanics: retention, event source mapping to Lambda, batch size vs reserved concurrency, and dead-letter queues.

Updated Aug 29, 2026

AWS Step Functions

Express Workflows and the at-least-once delivery guarantee that makes idempotency mandatory, not optional, for every step.

Updated Aug 29, 2026

Amazon VPC

CIDR math, what actually makes a subnet public, NAT Gateway vs NAT Instance, security groups vs NACLs, Elastic IPs, and SSH agent forwarding, all in one place.

Updated Aug 29, 2026

AWS WAF

Attaching a web application firewall at CloudFront, the one place every request already passes through, and a pricing gotcha to watch for.

Updated Aug 29, 2026

AWS | Durgesh Rai