Senior Software Engineer

Kunai builds full-stack technology solutions for banks, credit and payment networks, infrastructure providers, and their customers. Together, we are changing the world’s relationship with financial services. At Kunai , we help our clients modernize, capitalize on emerging trends, and evolve their business for the coming decades by remaining tech-agnostic and human-centered.

We are seeking a Senior Software Engineer to join a high-impact digital payments modernization program supporting the integration of a major card network into one of the largest financial institutions in the United States. This is a hands-on engineering role at the intersection of legacy and modern infrastructure, where you will contribute to both the reliability of mission-critical payment systems today and help shape the architecture that will power them tomorrow. You will work across scalable backend services, performance testing frameworks, and application engineering — with real opportunity to grow your skills on modern cloud-native technologies as the program evolves.
WHAT YOU'LL DO

You will be embedded across one or more workstreams supporting digital payments engineering, with responsibilities that may include:
Scalability, Performance Testing & Validation

- Design and execute enterprise-grade performance testing strategies for payment processing services, defining frameworks, tooling, and success criteria from the ground up.

- Identify performance bottlenecks across legacy and modern service layers and drive measurable improvements through analysis and targeted optimization.

- Instrument and validate services running on Java, Oracle, Tomcat, and WebSphere as well as modern workloads running on PostgreSQL and OpenShift.

- Collaborate with backend engineers to ensure scalability requirements are met across all environments prior to release.

- Translate performance findings into clear recommendations for engineering leads and stakeholders.

Application Engineering

- Build and maintain full-stack backend services supporting card network integration, working primarily in Java with PostgreSQL and OpenShift Container Platform (OCP).

- Contribute to application modernization efforts, migrating and re-platforming services from legacy infrastructure to cloud-native environments.

- Leverage AI-assisted development tooling (including GitHub Copilot) to improve development velocity and code quality.

- Participate in code reviews, architectural discussions, and cross-team technical planning sessions.

General Engineering

- PCI data purging pipelines and event-driven architecture patterns including token removal and event consumption.

- Work with event-driven services running on OpenShift and Oracle and PostgreSQL backends to support data lifecycle and compliance requirements.

- Serve as a flexible, senior contributor across teams where engineering depth and experience are needed most.

REQUIRED SKILLS & EXPERIENCE
Core Engineering

- 5+ years of professional software engineering experience, primarily in Java.

- Strong working knowledge of relational databases — Oracle and/or PostgreSQL required.

- Experience deploying and operating services in containerized environments (OpenShift, Kubernetes, or equivalent).

- Familiarity with legacy enterprise application servers — Tomcat and/or WebSphere experience a plus.

Performance Engineering

- At least one enterprise-level performance testing engagement — defining strategy, selecting tooling, executing tests, and presenting findings.

- Experience with performance profiling, load testing, and bottleneck resolution in high-throughput, distributed systems.

- Ability to design logical, streamlined test frameworks from scratch and operate with minimal guidance.

Payments & Financial Services

- Background in digital payments, card processing, or financial services technology strongly preferred.

- Understanding of PCI compliance requirements and secure data handling practices.

- Familiarity with