Practice: Design Instagram

Photo and video sharing platform inspired by Instagram's published engineering: stateless app servers, media in object storage behind a CDN, sharded Postgres with shard-encoded ids, precomputed feeds and async processing. A teaching design, not Meta's current internal architecture.

Build this system yourself on the canvas below. Add components, connect them, and run traffic simulations to see where your design holds up and where it breaks.

Functional requirements

  • Users can upload photos and videos.
  • Users can follow and unfollow other users.
  • Users can like and comment on posts.
  • Users can view a personalized news feed.
  • Users receive notifications for likes, comments, and follows.
  • Users can search users, hashtags, and posts.
  • Users can view media quickly from anywhere in the world.

Non-functional requirements

  • System should support hundreds of millions of users.
  • Feed loading latency should be under 200ms.
  • Media uploads should be reliable and resumable.
  • System must scale horizontally.
  • High availability with 99.99% uptime.
  • Media delivery must be globally optimized.
  • System should tolerate node failures without downtime.
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System Design Interview
Round 1 of 4 · Architecture Design · 60:00 remaining
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Design Your Own System
Phase 01: Thinking in Systems
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Components

User
CDN
Load Balancer
Server
Cache
Database
Blob Storage
Search Index
Queue
Worker
Rate Limiter
Service
API Gateway
Reverse Proxy
WebSocket Server
Third-party API

Inspector

Notes
Use clear names so your design intent is easy to understand.
Good
Name by business meaning
"Order API", "Restaurant Service"
Avoid
Generic names = zero signal
"Server 1", "API", "Queue"
A short description for each component makes feedback much better.
100%
Start by identifying:
  • Users & entry points
  • APIs & services
  • Databases & storage
  • Traffic flow & scale

Round 1 of 4 Architecture Design

Run a simulation to see results.

Time Remaining
60:00
System Design Interview

What are the core functional requirements?
What are the key non-functional constraints?

Questions

Start Evaluation to unlock questions.

Components Added
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Click "+ Add" to document components introduced in this stage.
Design Decisions

Click Simulate to run your design and see results here.

Internal notes — not shown to learners.

EVALUATE MODE

Test yourself like it's the real thing.

A structured 4-module evaluation that mirrors how top companies assess system design candidates.

Architecture Design
Draw your system on the canvas. Define components, connections, and data flow.
FR & NFR Requirements
Answer functional and non-functional requirement questions about your design.
MCQ Round
Multiple choice questions testing your depth on the chosen system.
Tradeoff Analysis
Justify your design decisions and defend your architectural tradeoffs.
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Round 2 of 4
MCQ Round
Answer multiple-choice questions based on your design.

Exit Interview?

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Your progress will be saved.

Open a saved design

Select a design to load into the canvas.

My Evaluations

Your past evaluation sessions

Here’s a simple request flow that follows the expected layer order.

External User
→
Edge CDN → API Gateway → Load Balancer
→
Compute App Servers / Services
→
DataAccess Cache
→
Storage Database / Search Index
→
Async Queue → Worker

Tip: keep arrows moving forward through layers (Edge → Compute → Storage). Avoid sending storage back to compute.

Evaluation Instructions

Read the rules carefully before starting. The test auto-submits on refresh.

Before you start

  • Build your architecture on the canvas. The timer starts when you click Start Evaluation.
  • Don't forget to answer Functional Requirement and Non Functional Requirements.
  • When satisfied with your design, click Next to lock it and view the questions.
  • Please answer final step questions to complete the evaluation.

Dos

  • Do read each question carefully before answering.
  • Do include required components to maximize component coverage.
  • Do save a copy of your design if you want to keep it before submission.

Don'ts

  • Don't refresh or close the tab during an active evaluation — this will auto-submit your answers.
  • Don't switch app modes or open another tab while the evaluation is running.
  • Don't attempt to edit the design after clicking Next; the workspace will be locked.

All the best!!

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    SYSTEM BRIEF

    ⬤ System Constraints

    What the system must do — every item is a user-facing behaviour your architecture must support.

      ↑ Engineering Constraints

      These are the failure modes you must design against — latency SLAs, durability targets, traffic ceilings.

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