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🎯 What Great Case Studies Show

A great case study demonstrates how you think, not just what you built. Here’s what separates good from great:
AspectGood ❌Great ✅
Problem”Built an e-commerce site""Solved inventory sync across 3 warehouses with 99.9% accuracy”
Architecture”Used React and Node""Chose React for SEO with Next.js SSR, Node for real-time WebSocket support”
Trade-offs”Used PostgreSQL""PostgreSQL over MongoDB for ACID transactions; accepted slower writes for data integrity”
Impact”It works""Reduced checkout time by 40%, handled 10K concurrent users”
Think like a Staff Engineer: Every decision should answer “Why this? What were the alternatives? What would you do differently?”

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📋 Required Sections

Overview

Purpose: Quick snapshot for readers to understand what this is about
  • Project name and one‑line value proposition
  • GitHub link(s) with good READMEs
  • Live demo URL (if applicable)
  • Team size and your role
  • Timeline (e.g., “3 months, part-time”)

Goals of the Project

Purpose: Show you understand the business context, not just code
  • Business/User Goals: What problem does this solve? Who benefits?
  • Technical Goals: Performance targets, scalability requirements
  • Non-Goals: What’s explicitly out of scope? (Shows scoping skill!)
## Goals
- Support 10K concurrent users with <200ms latency
- Process payments with PCI compliance
- Real-time inventory updates across warehouses

## Non-Goals
- Mobile app (web-responsive for MVP)
- International shipping (US-only for v1)

System Architecture Overview

Purpose: Give readers the 10,000ft view before diving inTech Stack Table (required):
LayerTechnologyWhy This Choice
FrontendNext.js 14SSR for SEO, App Router for better DX
BackendNode.js + ExpressTeam familiarity, WebSocket support
DatabasePostgreSQLACID for payments, JSONB for flexibility
CacheRedisSession storage, rate limiting
PaymentsStripeBest docs, webhook reliability
Architecture Diagram (use Mermaid):

Key Features

Purpose: Show depth in each domain you builtGroup by domain with bullet points:Authentication & Authorization
  • JWT with refresh token rotation
  • Role-based access (Buyer, Seller, Admin)
  • OAuth2 with Google and GitHub
Payments
  • Stripe Elements for PCI compliance
  • Webhook handling for async confirmations
  • Refund flow with seller approval

Flows & Diagrams

Purpose: Show you can visualize complex interactionsInclude 2-3 key flows:
  • User Flow: Happy path for main use case
  • System Flow: How services communicate
  • Error Flow: How you handle failures

API & Data Design

Purpose: Show you can design clean interfaces and data modelsImportant Endpoints (grouped by domain):
# Products
GET  /api/products        → List products with filters
POST /api/products        → Create product (seller)

# Orders
POST /api/orders          → Create order
GET  /api/orders/:id      → Get order details
PATCH /api/orders/:id     → Update order status
Database ERD:

Challenges & Solutions

Purpose: This is the GOLD - shows your problem-solving abilityInclude 5-10 specific challenges with:
  • What was the problem?
  • Why was it hard?
  • How did you solve it?
  • What trade-offs did you make?
ChallengeSolutionTrade-off
Inventory oversellingOptimistic locking with version numbersSlight UX friction on conflicts
Slow product searchElasticSearch with async indexingAdded infrastructure complexity
Payment webhook failuresIdempotent handlers + dead letter queue5-min delay for failed retries

Best Practices

Purpose: Show you know production-grade engineering
  • Security: CSRF tokens, rate limiting, input sanitization, SQL injection prevention
  • Performance: CDN caching, DB indexing, query optimization, lazy loading
  • DX: TypeScript, ESLint, Prettier, pre-commit hooks, CI/CD
  • Observability: Structured logging, error tracking (Sentry), metrics (Prometheus)

Conclusion

Purpose: Summarize impact and show growth mindset
  • Outcomes/Metrics: Load time improved 60%, handled 10K users, 99.9% uptime
  • Learnings: What would you do differently?
  • Next Steps: What features would you add next?

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📊 Rubric (What Mentors Look For)

CriteriaWeightExcellentNeeds Work
Clarity of Writing20%Clear, concise, well-organizedRambling, unclear structure
Technical Depth30%Shows deep understanding of tech choicesSurface-level descriptions
Architecture Reasoning30%Explains trade-offs, alternatives considered”I used X because it’s popular”
Evidence20%Diagrams, code refs, metrics, demosText-only, no proof

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💡 Pro Tips

Long enough to be comprehensive, short enough to be readable. Link out to code rather than pasting large snippets.
Start each section with WHY it matters. “Reduced checkout time by 40%” is better than “Implemented checkout flow.”
Screenshots, GIFs, diagrams > paragraphs of text. A well-labeled architecture diagram is worth 1000 words.
Saying “MongoDB was wrong for our use case, we migrated to PostgreSQL” shows maturity, not weakness.
Have a mentor or peer review before submitting. Fresh eyes catch unclear explanations.

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🚀 Ready to Write?

Template

Copy this template and fill in your project details

Example

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