Looking for Senior Developer – Shopify + Centralized Custom Checkout (EU Payments)

Hi everyone,


I’m looking for a senior developer to collaborate on a payment-heavy e-commerce project.

Project overview​

• Multiple Shopify Standard stores (used for catalog & inventory)
• Centralized custom checkout hosted on a single whitelisted subdomain
• Embedded card payment form (iframe, no redirect)
• Checkout receives sessions from multiple stores and processes payments centrally
• After successful payment, orders are created in Shopify via Admin API
• Strong focus on conversion rate, UX, and reliability

Tech scope​

• Backend for checkout session management and price validation
• Integration with an EU card payment gateway using embedded iframe
• Proper handling of server-to-server payment notifications
• Shopify Admin API (orders, inventory, customers)
• Clean, compliant architecture (no card data ever touches our servers)

Requirements​

• Proven experience with custom checkouts
• Solid experience with payment gateways (embedded / iframe based)
• Comfortable with Shopify Admin API
• Backend stack: Node.js or PHP
• Strong understanding of edge cases (idempotency, retries, partial failures)

Important​

This is not a basic Shopify task and not a template job.
I’m looking for someone who understands payments infrastructure, not just frontend.


DM me with:

• Relevant experience
• Preferred tech stack
• Availability

Serious developers only.

Hi, this project fits well with my experience.

I’ve worked on custom checkout systems, embedded iframe payments, and Shopify Admin API integrations, including centralized checkout flows and server-to-server payment handling. I’m comfortable with PCI-safe architectures, idempotency, retries, and handling edge cases in payment systems.

Tech stack: PHP (Laravel) / Node.js / Shopify
Availability: Ready to start and commit long-term

I’ve sent you a DM with more details and relevant experience.

Thanks.

fixer78 said:

Hi everyone,


I’m looking for a senior developer to collaborate on a payment-heavy e-commerce project.

Project overview​

• Multiple Shopify Standard stores (used for catalog & inventory)
• Centralized custom checkout hosted on a single whitelisted subdomain
• Embedded card payment form (iframe, no redirect)
• Checkout receives sessions from multiple stores and processes payments centrally
• After successful payment, orders are created in Shopify via Admin API
• Strong focus on conversion rate, UX, and reliability

Tech scope​

• Backend for checkout session management and price validation
• Integration with an EU card payment gateway using embedded iframe
• Proper handling of server-to-server payment notifications
• Shopify Admin API (orders, inventory, customers)
• Clean, compliant architecture (no card data ever touches our servers)

Requirements​

• Proven experience with custom checkouts
• Solid experience with payment gateways (embedded / iframe based)
• Comfortable with Shopify Admin API
• Backend stack: Node.js or PHP
• Strong understanding of edge cases (idempotency, retries, partial failures)

Important​

This is not a basic Shopify task and not a template job.
I’m looking for someone who understands payments infrastructure, not just frontend.


DM me with:

• Relevant experience
• Preferred tech stack
• Availability

Serious developers only.

Click to expand...

Hello,

This is exactly the kind of project I specialize in.

I’m a senior backend-focused developer with deep experience in payment-heavy e-commerce systems, including custom centralized checkouts, embedded/iframe-based card payments, and post-payment order creation via APIs.

Your architecture (multiple Shopify stores → centralized custom checkout → Admin API order creation) is familiar territory, including:
✔ Secure checkout session management
✔ Server-side price & inventory validation
✔ Embedded iframe payment gateways (no redirects)
✔ Webhook handling & S2S payment notifications
✔ Idempotency, retries, and partial-failure recovery
✔ Clean, compliant flow (no card data touching servers)

Backend stack: Node.js (preferred) or PHP
Strong focus on conversion rate, UX stability, and payment reliability.

This is clearly not a basic Shopify task, and I understand the risks and edge cases involved in payment infrastructure.

You can review my services here:
Sales Thread:
https://www.blackhatworld.com/seo/premium-development-automation-custom-websites-web-apps-ai-solutions-software-development-more-codiwiki.1732441/

I’ve sent you a detailed PM with relevant experience and availability.

Looking forward to discussing this.

fixer78 said:

Hi everyone,


I’m looking for a senior developer to collaborate on a payment-heavy e-commerce project.

Project overview​

• Multiple Shopify Standard stores (used for catalog & inventory)
• Centralized custom checkout hosted on a single whitelisted subdomain
• Embedded card payment form (iframe, no redirect)
• Checkout receives sessions from multiple stores and processes payments centrally
• After successful payment, orders are created in Shopify via Admin API
• Strong focus on conversion rate, UX, and reliability

Tech scope​

• Backend for checkout session management and price validation
• Integration with an EU card payment gateway using embedded iframe
• Proper handling of server-to-server payment notifications
• Shopify Admin API (orders, inventory, customers)
• Clean, compliant architecture (no card data ever touches our servers)

Requirements​

• Proven experience with custom checkouts
• Solid experience with payment gateways (embedded / iframe based)
• Comfortable with Shopify Admin API
• Backend stack: Node.js or PHP
• Strong understanding of edge cases (idempotency, retries, partial failures)

Important​

This is not a basic Shopify task and not a template job.
I’m looking for someone who understands payments infrastructure, not just frontend.


DM me with:

• Relevant experience
• Preferred tech stack
• Availability

Serious developers only.

Click to expand...

Hi, I have sent you a private message with my experience, tech stack, and availability. Please check it when you get a chance. Thank you

Hey, just sent you a PM, feel free to check it when you have a moment.
Our team has been working on web projects of all sizes since 2009. We'd be happy to assist you!

Our marketplace thread:
https://www.blackhatworld.com/seo/a...evelopment-partner-for-your-business.1452577/
*Please, note that we work on both, adult and mainstream projects.

fixer78 said:

Hi everyone,


I’m looking for a senior developer to collaborate on a payment-heavy e-commerce project.

Project overview​

• Multiple Shopify Standard stores (used for catalog & inventory)
• Centralized custom checkout hosted on a single whitelisted subdomain
• Embedded card payment form (iframe, no redirect)
• Checkout receives sessions from multiple stores and processes payments centrally
• After successful payment, orders are created in Shopify via Admin API
• Strong focus on conversion rate, UX, and reliability

Tech scope​

• Backend for checkout session management and price validation
• Integration with an EU card payment gateway using embedded iframe
• Proper handling of server-to-server payment notifications
• Shopify Admin API (orders, inventory, customers)
• Clean, compliant architecture (no card data ever touches our servers)

Requirements​

• Proven experience with custom checkouts
• Solid experience with payment gateways (embedded / iframe based)
• Comfortable with Shopify Admin API
• Backend stack: Node.js or PHP
• Strong understanding of edge cases (idempotency, retries, partial failures)

Important​

This is not a basic Shopify task and not a template job.
I’m looking for someone who understands payments infrastructure, not just frontend.


DM me with:

• Relevant experience
• Preferred tech stack
• Availability

Serious developers only.

Click to expand...

I have experience with custom checkouts and embedded payment gateways for Shopify.
Please DM me.

Hi there,

I have extensive experience working on custom checkouts and integrating payment gateways, particularly for Shopify-based e-commerce systems. I’ve handled complex scenarios like centralized custom checkouts, embedded card payment forms, and Shopify Admin API integrations.

Here’s a breakdown of how I can help:

• Custom Checkout Expertise: Built and optimized custom checkout flows, ensuring smooth user experience and high conversion rates.
• Payment Gateway Integration: Worked with EU card payment gateways using embedded iframes and properly handled server-to-server payment notifications.
• Shopify Admin API: Proficient in managing orders, inventory, and customers through Shopify’s Admin API.
• Tech Stack: Comfortable working with Node.js and PHP for backend development, ensuring clean, compliant architecture with no card data stored on the servers.
• Edge Cases Handling: I understand the importance of idempotency, retries, and partial failures in payment systems and have handled these effectively.

Let me know your availability and how we can collaborate on this project!

Hi,
I have understood your requirments.
I have sent you a proposal via DM.
Thank you.

Our team gives you a complete pacakge.

*Website design and development
*on-site seo
*technical seo
*off-site seo.

If you already have a website , no worries we can do the SEO part.

All handled inhouse .

Please get in touch if you're interested.