AlgoRhythm

A native iOS app for technical-interview prep with a swipe-to-study flashcard interface, an adaptive difficulty engine, and a serverless AWS backend.

Try it in your browser: ishraqb.github.io/AlgoRhythm

• iOS app (ios/): Swift / SwiftUI. Swipe right to mark a card mastered, left to flag it for review; tap to flip for the solution, code, and time/space complexity. Haptics and an optional rapid-fire tick keep sessions focused.
• Web app (web/): React + TypeScript (Vite) port of the same swipe deck and adaptive engine, running fully client-side with progress saved in the browser. Deployed to GitHub Pages via the workflow in .github/workflows/.
• Backend (backend/): AWS CDK (TypeScript) defining Cognito (email/password auth), AppSync (GraphQL), DynamoDB, and Lambda resolvers.
• Scripts (scripts/): pull free, attribution-licensed content (MBPP, system-design-primer) and seed it into DynamoDB.

For step-by-step run and deploy instructions, see DEPLOYMENT.md.

Architecture

SwiftUI app  ──(Cognito email/password)──▶  Cognito User Pool
     │
     └──(GraphQL + Cognito token)──▶  AppSync ──▶ Lambda resolvers ──▶ DynamoDB
                                                  (PK User_ID / SK Topic_ID)

The app is offline-first: the bundled questions.json always works with no network. Only user performance syncs to the cloud, and the server derives the owner from the verified token, so users can only read/write their own data.

Prerequisites

• Xcode 16+ (full app, not just Command Line Tools)
• Node.js 18+ and npm
• An AWS account with credentials configured (aws configure)

If Xcode was just installed, finish its component setup once:

sudo xcodebuild -runFirstLaunch
xcodebuild -downloadPlatform iOS

Run the iOS app

open ios/AlgoRhythm.xcodeproj

Pick an iPhone simulator and press Run. With no backend configured yet, the sign-in screen offers "Continue without an account" so you can try the deck locally. Progress stays on-device in that mode.

Deploy the backend

cd backend
npm install
npx cdk bootstrap          # one-time per account/region
npx cdk deploy --outputs-file cdk-outputs.json

Then generate the app config and seed content:

cd ../scripts
npm install
npm run ingest             # downloads MBPP + system-design-primer cards
TABLE_NAME=AlgoRhythm npm run seed
npm run write-config       # writes ios/AlgoRhythm/Resources/AppConfig.plist

Rebuild the app in Xcode and it will use real Cognito auth and cloud sync.

To tear everything down:

cd backend && npx cdk destroy

Content & licensing

• Original baseline cards are authored for AlgoRhythm.
• MBPP — CC-BY-4.0. system-design-primer (Donne Martin) — CC BY 4.0.
• Attribution is shown in-app on the Credits screen. No LeetCode scraping or copyrighted third-party problem text is used.

Cost

Designed to run at $0: free personal Apple ID sideloading and AWS free-tier services (Cognito, Lambda, AppSync, DynamoDB on-demand). No paid APIs.