What building my first SaaS (ProJamm) taught me that tutorials never did

I spent 6 hours debugging an issue that had nothing to do with Spring Boot, React, or my database.

The problem was… my assumptions.

That day made me realize how different building a real SaaS is from following tutorials.

Tutorials taught me:

• How to create APIs

• How to authenticate users

• How to connect frontend and backend

But when I started building ProJamm, a real project management SaaS, I ran into problems tutorials never warned me about:

1. Deleting a project broke half the system because of hidden entity dependencies

2. One feature change forced updates across permissions, roles, tasks, and UI

3. “Simple” features like task assignment became complex once real users were involved

4. My backend worked perfectly… until edge cases appeared

Nothing was technically wrong — but the system still failed.

Here’s what I learned the hard way:

Tutorials teach syntax. Products teach responsibility.

• Every decision has a blast radius

• Features are connected, not isolated

• “Later” technical debt arrives much sooner than expected

• Users don’t care how clean your code is — they care if it works

Most importantly:

You stop coding for correctness and start coding for survivability.

Here are concrete things building ProJamm forced me to learn:

Design before code
I now sketch entity relationships before writing a single class.

Think in flows, not endpoints

“Delete project” ≠ delete one row

It means members, roles, tasks, tokens, permissions, and notifications.

Fail-safe > feature-rich
I prefer a boring feature that never breaks over a fancy one that does

Logs are more important than code elegance

log.info("Deleting project {} with {} tasks", projectId, taskCount);

This saved me more times than refactoring ever did

Build like you’ll maintain it for years
Because once users depend on it, you will

If you’re building your first SaaS and feel like:

• everything is connected

• changes break unrelated features

• tutorials suddenly feel insufficient

You’re not doing it wrong — you’ve graduated from tutorials.

Building ProJam didn’t make me a perfect engineer.
But it taught me how real software behaves in the wild.

If you’re building something similar, I’d love to hear what surprised you the most.