Tried building my own booking system — where will I hit a wall, should I outsource to an agency?

Out of sheer stubbornness, I built a custom booking system for our clinic two years ago. By week two, two VIP clients booked the exact same time and bumped into each other in the lobby. One of them stormed out screaming and dropped a 1-star Google review. Shut the system down that very day and switched to commercial software. Total nightmare, absolutely not worth the grief.

The roadblock you're hitting is called a "race condition" in software. You have to temporarily reserve that slot while the user is on the checkout screen, and release it back after 10 minutes if the payment fails. Pulling this off reliably with amateur no-code tools is nearly impossible.

If you go to an agency to have this built from scratch, they'll open negotiations at 70,000 - 90.000 TL minimum. Paying 1,500 TL a month for a ready-made system takes about 4–5 years to break even on that cost. Plus, server crashes, updates, and SMS API changes are entirely the SaaS vendor's headache.

for sms you need an operator sender id with your tax certificate when webhook settings break no reminders go out clients dont show up wouldnt touch that with a ten foot pole tbh just stick to off-the-shelf platforms.

Put deposits and SMS aside for now. Start with free booking plugins that simply sync your specialists' Google Calendars. Once you're handling more than 20 appointments a day hire a pro team or subscribe to an established platform.

Who decided a 4-person salon needs custom software anyway? No need to reinvent the wheel. Thousands of salons around the world and in Turkey run on specialized vertical SaaS platforms. Spend your time on clients, not code.

couldnt we just write a simple script that automatically refreshes the page and hides the slot the moment a client submits the form to prevent double-booking?

Because you will be collecting identity, contact details, and records of aesthetic treatments, your custom software must fully meet your obligations as a data controller under KVKK. Any data breach leaves you wide open to administrative fines.

I feel the same way. Just because everyone does it doesn't mean it's right.

The answer above hits the nail on the head... honestly if you dont write this down from the start, it leads to arguments later.

If you have questions write them; I'll answer as best I can.

I don't think this advice fits everyone. Trying to do this alone is the most expensive way.

Hope this helps.

There's a trap here, let me mention it. The biggest time-waster for us was not knowing who had the final say.

Any unwritten clause becomes a point of disagreement later, as both sides remember it differently. If you post the result here, it will help others too.

Same here.

We got stuck at the same point for a while. If acceptance criteria aren't written, when the work is done is open to debate.

We got stuck at the same point for a while. Processes without records never improve, because you don't know what to fix.

Everyone rushing into setting up a booking system gets stuck at the same point. Just leaving this note, it might be useful.

Three different views emerged, they all complement each other. honestly solutions that work at a small scale collapse when you grow; I learned this late.

That's all sorry if I went on too long.

I've been dealing with this for a long time. Solutions that work at a small scale collapse when you grow; I learned this late.

If I were you, I'd go this route.

Saved. Payment schedules should be tied to project phases, not calendar dates.

Of course, it varies if your situation is different.