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[Anaya @Anaya_sharma876]

Interviewer:

How does a 10GB file become 2GB after zipping?

10GB → 2GB

Where did the other 8GB go?

[Uday👨‍💻 @uday_devops]

Interviewer:

You accidentally committed sensitive credentials. How would you remove them from the entire history?

[Virendra Patel @V1rendra_]

Many developers still don't know this
If you know then tell me..

Concurrency vs Parallelism

[Captain Insight @CaptainInsightX]

Frontend has screenshots.

Backend has... what?

How do backend developers show their work?

[Umesh Kumar Yadav @Umesh__digital]

Backend Developer interview:

We can write 80% of our code with AI why should we still hire you.

What will be your response?

[Sakshi Sugandhi @SakshiSugandhi]

Backend interview question:

Your service has been running for 5 years.

Zero downtime.
Millions of requests per day.

Today it suddenly starts returning cached data from 2 years ago.

No deploy.
No incident.
No cache changes.

Why?

[fidexCode @fidexcode]

Only programmers can answer this

[NOVA @Its_Nova1012]

I see many Developers still don't know this :-

Proxy vs Reverse Proxy

[Sakshi Sugandhi @SakshiSugandhi]

I see many Developers still don’t know this :-

Compile-time vs Run-time

[Mr Ash @ash_twtz]

If cooling is the biggest problem for data centers

So why aren't we building them under ice cream factories where cooling is abundant and free?

[Aditya @Aditya_181105]

97% vibe coder will fumble during interviews if asked what this is

[Akintola Steve @Akintola_steve]

Your API was moving mad fast in development.

The moment it got deployed to production everything suddenly became slow.

Latency increased.
Requests started timing out.

What do you think could have gone wrong?

[shaQuiba @NaazShaquiba]

Interviewer: You deployed your React app. It works locally, but breaks in production.
“What changed?” (Answer is NOT React )

[Captain-EO 👨🏾‍💻 @EOEboh]

System design question:

User logs out and
logs back in on another device
using the same old token.

What exactly failed?

- JWT never invalidated
- no token blacklist
- sessions not cleared
- expiry set too long

[Captain-EO 👨🏾‍💻 @EOEboh]

What's your go-to
testing framework?

a) Jest
b) Vitest
c) Playwright
d) Cypress
e) I don't write tests 🏃

[Captain-EO 👨🏾‍💻 @EOEboh]

As a developer, have you ever asked:

Why does a password reset link
expire after 15 minutes...

Even though your session
lasts 30 days?

[shaQuiba @NaazShaquiba]

Interviewer:

Your frontend is on localhost:3000 and backend on localhost:8000... so everything’s local, right?

why do you get a CORS error?

[Akintola Steve @Akintola_steve]

So one thing I’ll say briefly:

If your app revolves around:

• Payments
• Wallets
• Transfers
• Savings
• Investments
• Lending
• POS/Agency banking
• Crypto
• Payroll
• Cross border transactions

Then CBN compliance is your problem because you’re dealing with money movement and financial activities.

If you collect user data:
NDPC enters the chat.

If customers use your platform:
FCCPC enters the chat.

If businesses onboard on your platform:
CAC requirements enter the chat.

If users can transact:
KYC, AML, audit trails and proper transaction monitoring should already be part of your architecture from day one.

Most people are building products.
Government agencies are waiting to build cases 😂

[Sarthak @Sarthak4Alpha]

Interviewer:

Why does an API work in Postman but not in the browser?

[Bishal Nandi @LearnWithBishal]

7/ Turn Claude into an entire AI engineering team.

Prompt:
“You are now 4 elite AI agents working together on the same project:
• Architect
• Engineer
• Reviewer
• Optimizer

Each agent has a specific role:
• Architect → Design scalable system architecture
• Engineer → Build the implementation
• Reviewer → Perform senior-level code review
• Optimizer → Improve performance and scalability
Workflow:
Architect designs the system

Engineer builds it

Reviewer critiques and improves it
Optimizer makes it production-grade
Finally provide:
• Complete architecture
• Full implementation
• Review feedback
• Final optimized version
Think and collaborate like a world-class engineering team building a real startup product.”