URL shorteners look simple.
Take a long URL → generate a short code → redirect.
That’s it.
But what if two different links get the same short URL?
So I created a challenge on VibeCode Arena to test this.
And the results were surprising.
🚨 The Problem
At first glance, everything works:
- Generate a random short string
- Map it to the original URL
- Return the short link
Simple and clean.
But there’s a hidden issue.
⚠️ What Can Go Wrong?
In real-world systems:
• Random strings can collide
• Two users may get the same short URL
• One mapping can overwrite another
• Data gets lost or mixed
And suddenly:
👉 A short link redirects to the wrong website
👉 User trust is broken
👉 System becomes unreliable
🧠 Why This Happens
The problem is randomness without guarantees.
Just generating a random string does NOT ensure uniqueness.
And without proper checks:
👉 Collisions are inevitable
🤯 What I Observed
When AI models tried this challenge:
- Some generated random short codes
- Many ignored collision handling
- Some didn’t check existing mappings
- Very few ensured uniqueness properly
The code works.
But the system is not reliable.
🔍 The Real Issue
This is not just about shortening URLs.
It’s about:
• Uniqueness
• Data integrity
• Scalability
• Reliability
Because:
👉 One collision can break multiple links
💡 What a Better System Needs
A proper URL shortener should:
- Check for existing short codes
- Handle collisions safely
- Use hashing or encoding strategies
- Store mappings in a reliable database
- Scale for millions of URLs
This ensures:
👉 Every short link is unique
👉 No data is overwritten
🔥 Try My Challenge
I created this challenge to test real-world system thinking.
👉 Try it here:
https://vibecodearena.ai/duel/d3e31c10-30b4-4d61-895f-d2751e71eaaf
Can you:
- Prevent duplicate short URLs?
- Handle collisions properly?
- Design a scalable system?
🎯 Final Thought
URL shorteners don’t fail because of code.
They fail because of edge cases and scale.
And that’s where real engineering begins.
Try it and tell me 👇
Did AI handle uniqueness properly… or create duplicate links?
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