Senior Backend Developer (Card Payment Systems)
Read straight from Roofstacks's careers page, verified 9h ago.Seekless can tailor your résumé to it.
Seekless can write your résumé for this posting first.
Before you apply
Locationİstanbul
Work modehybrid
Typefull-time
SenioritySenior
Experience5+ yrs
DepartmentRoofMoney, Kart Paketi
Company size51–200 people
PostedJun 27, 2025 · 1y ago
Verified live9h ago
May no longer be actively hiring
Posted by the company on Jun 27, 2025100% of this company's open roles have been listed for 90+ days
At a glanceSummarised by Seekless from the posting.
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
Hands-on with RESTful API, Webhook integrations
Strong debugging, testing, and system integration skills
Prior banking or fintech experience is highly preferred
Good command of English is a plus
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
Skills
C#
.NET Core
.NET Framework
SQL
PL-SQL
RESTful API
Webhook
Java
Python
Kotlin
TCP/IP
OAuth2
OpenID Connect
JWT
JWS
3DS SDK
ACS
About the company
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