Expert C++ Engineer

Ciklum

Remote, Poland

About the role:

As a Expert C++ Engineer, become a part of a cross-functional development team engineering experiences of tomorrow. Platform Payments team responsible for the systems that power credit card, gift card, chip-and-PIN, and alternative payment methods across our Client’s global platforms.

You will work on a large, mature C++ codebase that spans multiple generations of the language (from C to modern C++23), helping to improve its performance, reliability, security, and maintainability while supporting ongoing business growth.

Responsibilities:

Design, implement, and maintain features in a high-throughput payment processing platform;
Develop and integrate payment gateways such as Braintree, Adyen, Klarna, Shift4, MPGS, and others;
Implement security-critical functionality including encryption, secure data handling, and PCI-compliant workflows;
Optimize transaction processing pipelines for performance, scalability, and reliability;
Build and maintain automated tests including unit, integration, and security-focused tests;
Investigate, debug, and resolve production issues in a complex legacy system;
Collaborate with payment operations and business teams to onboard new payment methods and providers;
Ensure systems meet PCI-DSS and financial industry compliance standards;
Participate in on-call rotations to support production payment systems;
Contribute to ongoing modernization efforts, migrating legacy code toward newer C++ standards.

Requirements:

7+ years of professional experience with C++ in production systems;
Strong understanding of systems programming, including memory management, concurrency, and performance optimization;
Experience working with financial or payment processing systems;
Experience with Claude Code;
Solid knowledge of security best practices, including cryptography and secure handling of sensitive data;
Experience working with large, legacy codebases;
Strong debugging and troubleshooting skills;
Familiarity with HTTP/HTTPS and RESTful APIs;
Experience with Linux/Unix environments;
Knowledge of Apache modules;
Working knowledge of build systems, with Bazel being a strong advantage.