TL;DR
Most beginner backend issues come down to 5 things:
- messy APIs that don’t scale
- weak SQL habits
- security added too late
- no code structure
- bad error handling
Fix these early and you’ll already be ahead of most juniors.
When you start backend dev, the goal is simple: make it work.
And honestly, that’s fine at the beginning.
But after reviewing a lot of student projects, you start noticing the same patterns over and over again.
Here are the most common ones.
🧵 APIs that “work”, but don’t scale
Most beginners build APIs that return everything, everywhere, all the time.
You’ll see things like:
- endpoints that dump full database objects
- no pagination at all
- multiple DB calls for simple requests
It’s not a problem… until traffic grows or data increases.
Then everything slows down, and nobody understands why.
🧵 SQL used without thinking
SQL is usually learned fast, then ignored in practice.
Common patterns:
-
SELECT *everywhere - no indexes
- joins stacked without thinking about cost
- “it works on my machine” queries
It’s fine for small projects, but it doesn’t scale.
🧵 Security added at the end (if at all)
A lot of projects treat security like a final step.
That leads to:
- plain text passwords
- no validation on inputs
- weak or incorrect JWT handling
- no rate limiting
Security should be part of the design, not a patch.
🧵 No real structure in the code
Everything ends up inside controllers.
At first it feels fast.
Then:
- logic gets duplicated
- nothing is reusable
- testing becomes painful
- adding features starts breaking things
That’s usually the moment people discover “clean architecture” exists.
🧵 Error handling that doesn’t help
This one is very common.
- everything returns 500
- no logs
- useless error messages
- no distinction between client and server errors
When something breaks in production, debugging becomes guesswork.
💬 Final thoughts
None of this is dramatic. Everyone goes through it.
The real issue is staying in that phase too long.
If you fix even half of these early, you’ll already be ahead of most junior backend devs.
🤝 Let’s build better backend habits together
I’m trying to collect real-world mistakes and patterns from devs at all levels.
If you’ve seen other common backend mistakes (or made some yourself 😅), drop them in the comments.
Let’s build a list that actually helps juniors improve.
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