I Replaced My Side Project Backend with AI — Here’s What Broke First

If you’ve been on the internet for more than 5 minutes lately, someone has told you:

“Bro, AI can write your entire backend now.”

So obviously, I believed them.

I decided to run a small experiment:

Could I replace most of my side project backend logic with AI-generated code and prompts?

Short answer: yes.

Long answer: oh no.

Let’s talk about what broke first.

🧪 The Setup

Side project:

• Simple backend (CRUD + auth + notifications)


• Nothing fancy, just something that worked
  


• Stack: REST APIs, database, some business rules that were… let’s say “grown organically”

The plan:

• Use AI to generate controllers, services, and even some validation logic


• “Clean it up later” (famous last words)


• Move fast, break things — preferably not production

🚨 Thing #1 That Broke: Assumptions

AI is amazing at writing code.

AI is terrible at understanding your assumptions.

Example:

• I said: “Generate an endpoint to send notifications.”
  


• AI said: “Sure, I’ll retry failed notifications infinitely.”
  

Infinitely.

No backoff. No limits. No circuit breaker.

Just pure optimism.

Turns out AI assumes:

• Network calls always recover


• External systems are friendly


• Rate limits are a suggestion

Reality disagrees.

🔐 Thing #2 That Broke: Security (Quietly)

Nothing crashed.

No errors.

No alarms.

Which is exactly why this was scary.

AI happily:

• Exposed internal IDs


• Logged sensitive payloads


• Skipped edge-case auth checks because “it looked redundant”

The code was clean.

The vulnerability was invisible.

Lesson learned:

If you don’t explicitly say “this is security-sensitive”, AI assumes it’s a tutorial.

🧩 Thing #3 That Broke: Business Logic Nuance

This one hurt emotionally.

I asked AI to:

“Validate whether a user is eligible for an action.”

AI:

• Checked basic conditions


• Missed why those conditions existed in the first place

Humans encode intent in ugly if-statements.

AI encodes patterns.

That difference matters more than I expected.

🧠 The Surprising Win

Here’s the twist.

AI was incredible at:

• Boilerplate


• DTOs


• Mappers


• Test case scaffolding


• Explaining my own code back to me
  

It didn’t replace me.

It removed the parts of the job I secretly hated.

🧠 What I’d Do Differently Next Time

If you’re tempted to do this (and you should try it once):

✅ Use AI for:

• Skeletons


• Repetitive logic


• Tests


• Documentation

🚫 Don’t blindly trust it for:

• Auth


• Retries


• Money


• “This edge case only exists because of a 2021 incident”

Basically:

AI is a brilliant intern. Not your tech lead.

🎯 Final Take

AI didn’t break my backend.

My overconfidence did.

But honestly?

I’ll still use it again tomorrow.

Just with better prompts… and more tests.