System Design Framework – A Simplified 6-Step Method

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🧠 Welcome to Episode 2 of our series – High-Level System Design: A Simplified Guide
🎥 Watch the episode on YouTube

In this post, we’ll explore a 6-step mental model that simplifies any system design problem — whether you’re preparing for interviews or building scalable, real-world products.

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🚀 Why You Need a System Design Framework

System design interviews are intentionally vague.

You're told:

“Design a pastebin”
“Design a ride-sharing app”

But where do you even begin?

The mistake many engineers make is to jump directly into databases, APIs, or buzzwords. That’s like starting a building by placing bricks without a blueprint.

You need a framework — a repeatable approach that brings clarity and structure.

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🧩 Step-by-Step: The 6-Step System Design Framework

1️⃣ Clarify Requirements

Start by understanding what you're building — not how.

Ask:

• What are the functional requirements?

• What are the non-functional constraints (latency, availability, scale)?

• What are the edge cases, user types, and data retention policies?

🧠 Example: Designing Pastebin? Ask:

• Can pastes expire?

• Are they private/public?

• How many pastes per second?

👉 The quality of your design starts with the quality of your questions.

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2️⃣ Define APIs

Before diving into architecture, define the interfaces.

This makes the problem smaller and modular.

🧱 For Pastebin:

POST /paste
GET /paste/:id

Also address:

• Idempotency – Should retries create duplicates?

• Versioning – How do you evolve APIs?

• Rate limits – How do you prevent abuse?

We'll go deeper into these topics later in the course.

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3️⃣ Design the Database

Now decide:
→ Should it be SQL or NoSQL?
→ Do you need joins or flexibility?

📌 General rule:

• Use SQL when: data is relational, needs strong consistency (e.g., orders, billing)

• Use NoSQL when: flexible schema, massive scale, high write load (e.g., Pastebin content)

🧠 Pastebin Schema (NoSQL):

jsonCopyEdit{
  "id": "xyz123",
  "content": "Text content",
  "expires_at": "timestamp"
}

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4️⃣ Estimate & Handle Scale

This step separates junior engineers from senior ones.

Estimate:

• QPS (queries per second)

• Storage (daily/weekly/monthly growth)

• Bandwidth (data in/out)

🧠 Pastebin:

• 10M pastes/day × 1 KB = 10 GB/day

• 100K reads/sec = requires caching

Design for scale using real numbers, not assumptions.

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5️⃣ Add Async Components

Offload non-critical operations to background workers.

🧠 Examples:

• Archiving expired pastes

• Sending notifications

• Pre-processing data

Use tools like:

• Kafka, SQS (queues)

• Cron jobs

• Event-driven microservices

This helps:

• Improve responsiveness

• Isolate failure

• Allow retries and decoupling

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6️⃣ Identify Bottlenecks & Tradeoffs

Good design is not perfect design. It’s well-balanced design.

👉 Key trade-offs to consider:

Great engineers don’t avoid trade-offs. They make conscious choices with full awareness of their impact.

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🧠 Recap: The 6-Step Framework

Here’s a quick recap of the framework:

1. Clarify Requirements

2. Define APIs

3. Design the Database

4. Estimate & Handle Scale

5. Add Async Components

6. Identify Bottlenecks & Tradeoffs

This framework applies to almost every backend system — from Uber to Instagram to UPI.

📢 Coming Up in Episode 3:
We’ll go deeper into breaking down requirements, using real-world examples.

Thanks for reading. Let’s simplify system design — one concept at a time.

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✍️ Written by Rajdeep Dutta
🎓 TechSimplified by Rajdeep

#SystemDesign #SoftwareEngineering #Backend #FAANGPrep #Microservices #Architecture #TechSimplified