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I will develop, fix custom API integration payment gateway and webhooks
Marcel Dev
About this gig
Is your payment flow broken, incomplete, or missing entirely? Failed transactions, silent webhook failures, and unreliable API connections cost you sales and damage customer trust.
We build and fix the connective layer that makes your product actually work so payments process correctly, external services stay in sync, and your app responds to real-time events without manual intervention.
WHAT WE DELIVER:
- Custom REST API development and integration
- Payment gateway integration (Stripe, PayPal, Paystack, Flutterwave, etc.)
- Webhook setup for real-time event handling
- Secure authentication
- Clear documentation for your team
WHY IT MATTERS TO YOU:
- Transactions that process reliably, with proper error handling
- Root-cause fixes, not temporary patches, when something's broken
- Secure, well-documented endpoints your team can maintain long after delivery
WHY MARCEL DEVS:
We're a backend-focused development team payment flows and API integrations are core to what we build daily, not a side add-on.
Have a specific provider, API, or a broken integration in mind? Send us the details and we'll confirm scope before you order.
Get to know Marcel Dev
Marcel Dev
Full Stack Devs and Custom Software Developers
- FromGermany
- Member sinceSep 2026
- Avg. response time1 hour
Languages
German, English, Spanish
Marcel Devs, full-stack app & backend development team building secure, scalable software for businesses. We help companies replace disconnected systems with centralized, process-driven ERP and enterprise applications. We specialize in ERP consultation, business process automation, workflow optimization, fintech apps, and custom ERP development aligned with real business goals. We work with agility, transparency, and quality using Scrum Agile. Looking for long-term freelance partnerships!
Other Software Development Services I Offer
FAQ
Which payment gateways do you work with?
Stripe, plaid, PayPal, Paystack, Flutterwave, and most major REST-based payment APIs. Let us know your provider before ordering to confirm compatibility.
My API or payment integration is broken, can you fix it without rebuilding everything?
Yes. We first review your existing code and logs to find the root cause, then fix or rebuild only the broken parts, we don't rebuild working code unnecessarily.
What are webhooks and do I need them?
Webhooks let external services, like your payment provider, notify your app instantly when something happens, such as a successful payment or subscription renewal. Most payment integrations need at least basic webhook handling to work reliably.
Can you integrate multiple payment providers?
Yes, this is available on our Premium package or as a custom quote depending on complexity.
Do you provide documentation after delivery?
Yes, we include API and webhook documentation so your team can maintain the integration going forward.
What do you need from me to start?
Your API keys or sandbox credentials, the platform or codebase you're integrating into, and which events need webhook handling.
