Mock APIs are supposed to help you move fast. But at some point, they start doing the opposite.
This post is about the hidden cost of fake data-and how to move forward without over-engineering a backend.
Why mock APIs feel great at first
Fake APIs let you:
- Build UI without waiting
- Test happy paths easily
- Avoid backend complexity
- Ship screens fast
They’re perfect early on.
The problems you don’t notice until later
Mock data hides important realities:
- Auth flows that always succeed
- No distinction between users
- No invalid states
- No logs when something breaks
- No way to answer: “What actually happened?”
The result?
Your frontend works… until it doesn’t.
The dangerous moment: demo day
This is usually when things snap:
- A stakeholder asks to refresh the page
- A QA script expects data to persist
- A login flow needs to behave like production
- An error happens and there’s nothing to inspect
Suddenly, fake APIs become blockers.
What developers actually want
Most frontend teams don’t want “a backend.”
They want:
- Real endpoints
- Real data
- Real auth
- Minimal setup
- No backend ownership
That’s exactly the gap ReqRes fills.
Try a real flow (no backend required)
The Notes example app shows a real auth + CRUD flow, powered entirely by frontend calls.
👉 https://app.reqres.in/examples/notes-app
Final thought
Fake APIs are a phase-not a destination.
When your app starts behaving like a real product, your backend needs to do the same.
Start here:
👉 https://app.reqres.in