Senior Backend Developer (Card Payment Systems)

At Roofstacks , we’re building innovative financial technologies that power seamless card experiences. We are now looking for a Senior .NET Developer to join our growing Card Payment Systems team. If you're passionate about banking, payments, and high-performance backend development—this opportunity is for you.

🧩 What You’ll Be Doing

You will take part in the full development lifecycle of our card platform, working on mission-critical services used in:

- Card application flows for Debit, Credit, Prepaid, Digital & Commercial cards

- Integrations with KKB/LKS , Decision Support, Analytics Solutions and onboarding systems

- Development of card lifecycle and transaction management services (issuance, renewal, limits, fraud, posting, fee, campaign, extre, DWH etc.)

- Secure integrations with payment schemes ( Visa, Mastercard, BKM, CUP, Discover ) and EMV scripting/PIN management

- POS ecosystem integrations ( TechPOS, Ingenico SDK , CAT transaction flows, parameter distributions)

- Real-time and batch transaction processing with high availability (99.9% uptime) requirements

- Working with ISO 8583 messaging, socket programming, TCP/IP protocols

- Supporting authentication flows via OAuth2 , OpenID Connect, JWT/JWS, and 3DS SDK/ACS

✅ What We’re Looking For

- Minimum 5+ years of experience in software development

- Bachelor’s degree in Computer Engineering , Software Engineering , or related field

- Strong experience in C# , .NET Core / .NET Framework

- Solid command of SQL / PL-SQL (Oracle preferred)

- Experience in multi-threaded applications and performance optimization

- Prior banking or fintech experience is highly preferred

- Hands-on with RESTful API , Webhook integrations

- Strong debugging, testing, and system integration skills

- Good command of English is a plus

⚙️ Nice-to-Have Experience

- Experience with other OOP programming languages (such as Java, Python, Kotlin, etc.)

- EMV transaction flow, 3DS 2.x, ACS and GO integration

- Encoding/decoding logic in card-based data formats

- High-performance architecture experience in financial transactions

- Familiarity with scheme compliance (Visa/Mastercard bulletins & updates)

- Experience in distributed system development

- Familiarity with TCP/IP Socket programming , encoding/decoding formats (hex, bcd, ebcdic)

- Understanding of HSM , key management, encryption flows is a plus