How to Build a Flexible Coupon Code System for Your Website (With Stripe)

Discounts and promotions are powerful for small businesses, but most off-the-shelf solutions are either too rigid or too expensive. So I built a custom coupon system that lives right on your site and gives you full control.

Here’s how it works under the hood (without getting too nerdy):

The system has three layers:

A PostgreSQL database table that stores all coupon details

A storage/service layer that handles the logic

API endpoints for the frontend and admin area

Key features include:

Percentage discounts or fixed dollar amounts

Ability to restrict a coupon to specific products (or make it site-wide)

Max uses and expiration dates

Automatic usage tracking (increments safely after a successful purchase)

Full admin management page to create, edit, or deactivate codes

One smart decision: we calculate the discount ourselves and pass the final price to Stripe. This gives us complete control and avoids sync problems between systems. If a coupon brings the price to $0, we can even skip Stripe entirely and create the account directly.

On the customer side, there’s a clean “Apply Coupon” field on the signup or checkout form with real-time validation and updated pricing.

This is one of those tools that pays for itself quickly — whether you’re running seasonal promotions, client referral discounts, or special offers for loyal customers.

If you’re tired of fighting with third-party cart plugins or paying extra every month for basic discount features, just reach out and we’ll set up a time to evaluate your current website. Send me a message through our contact form at https://fireytech.com/contact or give me a call at 918-258-3473. I’ll take a look at what you have, show you what’s possible, and we can talk specifics and pricing from there.