AWS Amplify

What it is

AWS Amplify is a set of tools and services that lets front-end web and mobile developers build and host full-stack applications on AWS without assembling every service by hand. It has two main parts:

Amplify Hosting: a Git-based workflow for building, deploying, and hosting web apps with continuous deployment. Amplify deploys the app to the AWS global CDN (Content delivery network)A network of servers in many locations that caches content close to users, so that pages, images, and video load faster and the origin server handles less traffic. Amazon CloudFront is the AWS CDN.Glossary entry (CDN).
Amplify backends: you describe the back end (authentication, data, storage, functions) in TypeScript code, and Amplify provisions the AWS resources for you, building on the AWS CDK.

Amplify also includes client libraries and UI components for web frameworks and mobile platforms.

Choose Amplify when a question describes a front-end team that wants to build and deploy a web or mobile app quickly, with sign-in, an API (Application programming interface)A defined way for one program to ask another for data or actions, such as a set of HTTPS requests and responses. Every AWS service is controlled through its API, which the console, the CLI, and the SDKs call for you.Glossary entry, and storage, and little AWS infrastructure work.

Amplify Hosting

Frameworks: server-side rendered (SSR) frameworks such as Next.js and Nuxt (others with an adapter); single-page apps such as React, Angular, and Vue.js; and static site generators such as Gatsby and Hugo.
Continuous deployment: connect a Git repository, and every commit to a branch builds and deploys automatically.
Feature branches: each connected branch gets its own environment, such as main for production and dev for staging.
Pull request previews: a temporary preview of each pull request for code review.
Custom domains, with a managed certificate that Amplify provisions or your own; redirects and rewrites. A single-page app with a client-side router needs a rewrite (200) rule that serves index.html for app routes, so deep links and page refreshes load the app instead of returning 404; a redirect (301 or 302) changes the URL in the browser instead.
Password-protected branches keep unreleased work private.
Firewall support: attach AWS WAF rules to the hosted site.

Amplify backends

You define resources in files such as amplify/auth/resource.ts and amplify/data/resource.ts:

Auth: Amplify deploys an Amazon Cognito user pool for sign-up, sign-in, MFA (Multi-factor authentication)Signing in with two or more different kinds of proof, such as a password plus a code from a phone app or a security key. AWS recommends MFA for the root user and for every human user.Glossary entry, and social sign-in.
Data: typed real-time APIs powered by AWS AppSync (GraphQL), with data in Amazon DynamoDB.
Storage: files in Amazon S3.
Functions: business logic in AWS Lambda.

Each developer can use a cloud sandbox for testing, and shared environments map to Git branches.

Security, resilience, performance, and cost

Security

Amplify sets up Cognito for users and authorization rules for data, such as owner-based access, so each user sees only their own records.
IAM controls who can manage Amplify apps; CloudTrail records Amplify API calls.
Use password protection for preview branches and AWS WAF for production sites.

Resilience

Hosted sites are served from the global CDN, and the back end uses managed, Regional services (Cognito, AppSync, DynamoDB, S3, Lambda) with no servers to look after.

Performance

The CDN caches static content close to users; SSR pages are rendered on demand.

Cost

Amplify Hosting charges for build minutes, data stored on the CDN, data transferred out, and, for SSR apps, request count and duration. There is a free tier for 12 months.
Back-end resources (Cognito, AppSync, DynamoDB, S3, Lambda) are billed by those services.

Monitoring

Hosting metrics and logs appear in CloudWatch, and build logs appear in the Amplify console.

Amplify or another option?

If the requirement is	Choose
Front-end team wants Git-based hosting and a full-stack backend fast	AWS Amplify
Host a static website with the most control	Amazon S3 with Amazon CloudFront
A managed GraphQL API only	AWS AppSync
A REST (Representational state transfer)A style of web API in which resources are named by URLs and handled with standard HTTP methods, such as GET, PUT, and DELETE, and the server keeps no session state between requests. Amazon API Gateway builds REST APIs.Glossary entry API in front of Lambda	Amazon API Gateway
User sign-up and sign-in only	Amazon Cognito
Test the app on real phones and tablets	AWS Device Farm

Reverse mindmap: when the question points here

Is it AWS Amplify?

Yes, when the question says
- Front-end developers build a full-stack app quickly leads to Amplify
- Host a React, Angular, Vue, or Next.js app with CI/CD leads to Amplify Hosting
- Deploy on every Git commit leads to Amplify Hosting
- Preview environment for each pull request leads to PR previews
- SPA deep links return 404 leads to Rewrite (200) rule to index.html
Know what it builds on
- Sign-up and sign-in leads to Amazon Cognito
- Real-time GraphQL data leads to AWS AppSync with DynamoDB
- File uploads leads to Amazon S3
- Backend logic leads to AWS Lambda
No, when the question says
- Full control of a static site and its CDN leads to S3 with CloudFront
- Test on real devices leads to Device Farm

Key takeaways

Amplify helps front-end web and mobile developers build and host full-stack apps on AWS.
Amplify Hosting gives Git-based continuous deployment to a global CDN, feature-branch environments, PR previews, custom domains, and WAF.
Amplify backends are defined in TypeScript and provision Cognito (auth), AppSync and DynamoDB (data), S3 (storage), and Lambda (functions).
Hosting is billed for build minutes, storage, data transfer, and SSR requests.