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Fiverr Pro
English
$
USD
I will build a secure payment checkout and ecommerce integration
Eric Wang
About this gig
I will build or integrate a secure ecommerce checkout and payment flow for your web application. I can connect PayPal, ECPay, Stripe, LINE Pay, or another API-based gateway, then implement order and payment status, signed webhooks, idempotent callbacks, sandbox testing, receipts, and deployment handover.
My production experience includes multi-tenant payment services, checkout pages, callback processing, PostgreSQL, Docker, FastAPI, .NET, Next.js, and Cloud Run deployments.
WHAT I CAN DELIVER
Checkout and order flow integration
Payment provider API and webhook handling
Signature validation, idempotency, and error recovery
Sandbox tests and production-readiness checklist
Source code, deployment notes, and handover documentation
Before development, I confirm the provider, country and currency, existing technology stack, checkout flow, and acceptance criteria. Each package covers a clearly defined phase; larger commerce systems are delivered in milestones.
Message me with your provider and current stack so I can recommend the right package.
Get to know Eric Wang
Eric Wang
AI Driven Full Stack Engineer and SaaS Automation Specialist
- FromTaiwan
- Member sinceSep 2020
Languages
English, Chinese
Senior software engineer and studio lead with 25 years of experience, specializing in AI-driven development automation. At HurricaneSoft, one engineer plus an AI co-pilot team shipped 14+ production products in a single year, taking SaaS from zero to live in as little as 23 days.
I automate the full delivery lifecycle and build with .NET 8, Blazor, FastAPI, Next.js, GCP Cloud Run, multi-tenant SaaS, OAuth2/OIDC, LLM gateways and payments. Need a SaaS from scratch, a legacy system modernized, or an AI platform integrated? I deliver full-team output: fast, secure and production-grade.
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FAQ
Which payment providers can you integrate?
I can integrate PayPal, ECPay, Stripe, LINE Pay, and other API or webhook-based gateways after reviewing their documentation and regional requirements.
Can you integrate payments into an existing application?
Yes. I can add a secure checkout to an existing web application or build a standalone payment service, subject to reviewing the current stack and available APIs.
How do you test payment security and reliability?
I use the provider sandbox first, verify webhook signatures, make callbacks idempotent, handle retries and failures, keep secrets out of source code, and provide a production handover checklist.
What information do you need before starting?
Please provide the payment provider, country and currency, current technology stack, checkout and order flow, webhook requirements, sandbox access through a secure channel, and acceptance criteria.
