💼 Hiring Quest – Senior Backend Engineer (.NET) @ MoneyFellows

👋 We are MoneyFellows, a fintech product company transforming how people save, plan, and manage money through secure, scalable digital financial solutions.
Our mission is to build reliable financial platforms that operate at scale while maintaining high standards of performance, security, and engineering excellence. (MoneyFellows)

We’re hiring a Senior Backend Software Engineer (.NET) (5+ YOE) to join our backend team and help design, build, and optimize the core systems behind our products.

🕓 Start Date: Immediate

💰 Salary: USD 1400 - 1900
🌍 Location: Hybrid – 5th Settlement, Cairo

🛠️ How the Hiring Quest Works

1️⃣ Register for the quest

2️⃣ Receive the full challenge after registration closes

3️⃣ Submit your solution before the deadline

4️⃣ Top candidates are invited to a technical review session

5️⃣ One candidate will be hired

🔍 Who We’re Looking For

1. ✅ 5+ years of experience in .NET development or other OOP languages

2. ✅ Strong experience building and maintaining APIs, Microservices, and Databases

3. ✅ Solid understanding of Clean Architecture and modular system design

4. ✅ Hands-on experience with DDD (Domain Driven Design) concepts

5. ✅ Experience with Message Queues and Event Driven Architecture

6. ✅ Strong background in database profiling and optimization (RDBMS & NoSQL)

7. ✅ Familiar with CI/CD pipelines, cloud providers (AWS or Azure), and API security

8. ✅ Comfortable working with GitHub, EF Core, and modern development workflows

💡 Bonus: A/B testing, serverless concepts, monitoring tools, fraud detection, SonarQube or similar code quality tools

🎯 Your Mission: “Event-Driven Financial Transactions Platform”

🧠 Business Context

MoneyFellows systems deal with financial transactions, where:

1. Services must be independently deployable

2. Data consistency must be handled safely

3. Events must never be lost or duplicated

4. The system must be extensible for future financial modules

In this quest, you’ll design and implement a mini event-driven backend platform that reflects real-world fintech challenges.

📌 The Challenge

1️⃣ Step 1 — Domain Modeling (DDD)

Model two bounded contexts:

A) Transactions Context

1. Create Transaction

2. Add Transaction Items

3. Submit Transaction

4. Cancel Transaction (with clear business rules)

B) Payments Context

1. Start Payment for a Transaction

2. Confirm Payment

3. Fail Payment

Requirements

1. Clear Aggregates and invariants

2. Domain Events such as:

   • TransactionSubmitted

   • PaymentConfirmed

   • PaymentFailed

3. Clean separation between bounded contexts

📄 Deliverable: DOMAIN.md explaining your domain decisions.

2️⃣ Step 2 — Microservices + Clean Architecture

Implement two .NET services:

Transactions Service

1. Endpoints:

   • POST /transactions

   • POST /transactions/{id}/items

   • POST /transactions/{id}/submit

   • POST /transactions/{id}/cancel

Payments Service

1. Endpoints:

   • POST /payments/start

   • POST /payments/{id}/confirm

   • POST /payments/{id}/fail

Architecture requirements

1. Clean Architecture layers (Domain / Application / Infrastructure / API)

2. No infrastructure dependencies leaking into domain

3. Explicit application use-cases

3️⃣ Step 3 — Event-Driven Workflow

Use a message broker (RabbitMQ preferred):

1. TransactionSubmitted → published by Transactions service

2. Payments service consumes event → creates payment intent

3. Payment result publishes:

   • PaymentConfirmed

   • PaymentFailed

4. Transactions service consumes events → updates transaction state

Reliability is key
✅ Implement Outbox Pattern (or equivalent)
✅ Idempotent event consumers
✅ Basic retry & dead-letter handling

4️⃣ Step 4 — Observability & Testing

Add:

1. Correlation IDs across HTTP & events

2. Structured logging

3. Health checks

4. Tests:

   • Domain invariant tests

   • Integration test covering the full happy path

🧱 Suggested Tech Stack

1. .NET 8 / ASP.NET Core

2. PostgreSQL or SQL Server

3. RabbitMQ

4. Docker Compose

5. Optional frameworks: MassTransit, Wolverine, or NServiceBus (justify your choice)

🧩 Example Flow

1️⃣ Create transaction
2️⃣ Add items
3️⃣ Submit transaction → event published
4️⃣ Payment started
5️⃣ Payment confirmed
6️⃣ Transaction marked as completed

🧰 What You Should Submit

📂 GitHub Repository

1. /src/transactions-service

2. /src/payments-service

3. docker-compose.yml

4. README.md

5. DOMAIN.md

6. Optional: ARCHITECTURE.md + diagram

📹 10-Minute Video

1. 3 min: Introduction + one complex backend challenge you solved

2. 7 min: Live demo + architecture explanation + event reliability strategy

📊 Evaluation Criteria

1. Architecture & DDD correctness – 25%

2. Event-driven reliability – 25%

3. Code quality & Clean Architecture – 20%

4. Microservices boundaries & APIs – 15%

5. Testing & observability – 10%

6. Documentation – 5%

✨ Bonus: retries & DLQ, elegant domain modeling, clear trade-off explanations

📩 After Submission

Top candidates will join a technical review session discussing:

1. Domain modeling decisions

2. Event consistency strategies

3. Scaling the system in real fintech production

👉 Final decision within 5 business days after the review.