Full Stack Engineer (Kotlin / GCP), Payments Connectivity

Cognizant; Comunidad de Madrid; On-site; EUR 70,000 - 110,000; Full time

Job summary

Cognizant Technology Solutions Corporation is seeking a backend developer to own features end-to-end in a payments-focused platform. You will design and implement RESTful APIs, webhook handlers, and secure data exchanges in a Google Cloud environment.

You will work with serverless and container-based infrastructure, define APIs, and manage CI/CD pipelines with GitHub Actions. Collaboration with platform teams and external providers is essential.

Qualifications

• Proficient backend developer with Kotlin (or Java ready for Kotlin).
• Experience with Google Cloud Platform (serverless, messaging, load balancing, security, secret management).
• Design and consume REST APIs and OpenAPI specs; work with API gateways.
• Solid understanding of webhook patterns, idempotency, retries and failure handling.
• Knowledge of encryption and secure data exchange practices.
• Experience with Infrastructure as Code using Terraform.
• Strong CI/CD discipline with GitHub Actions or equivalent.
• Good testing practices across unit, integration and contract tests; observability.

Responsibilities

• Design, build, and maintain backend services integrating with payment providers.
• Develop webhook and callback handlers for asynchronous events.
• Implement secure data exchange with encryption and secrets management.
• Define APIs following internal standards and automate checks.
• Ensure secure inbound/outbound traffic via API gateways and cloud controls.
• Manage cloud infrastructure as code and deploy serverless/container-based services.
• Build and improve CI/CD pipelines including testing and release automation.
• Support production with monitoring, incident triage, and root-cause analysis.
• Contribute to platform improvements and technical documentation.
• Collaborate with platform teams and external provider contacts.

Skills

Kotlin

Micronaut

Spring Boot

Google Cloud Platform

REST APIs

OpenAPI

Webhook patterns

Encryption and secure data exchange

CI/CD

Testing and observability

Infrastructure as Code

Tools

Terraform

GitHub Actions

API gateways

Job description

About the Role

You will join a team that builds and runs payment connectivity services integrating a large-scale online payments platform with external payment service providers. You will own features end to end across backend services, serverless components, cloud infrastructure, and CI/CD, and contribute to the customer-facing payment flows.

What You’ll Do

• Design, build, and maintain backend services that integrate with payment service providers for payment initiation and status retrieval.
• Develop and support webhook and callback handlers that process asynchronous payment events reliably and securely.
• Implement secure data exchange, including payload encryption and decryption and managed secrets.
• Define and maintain well-documented APIs that follow internal standards and are validated through automated checks.
• Secure inbound and outbound traffic using API gateway, edge, and cloud security controls.
• Manage cloud infrastructure as code and deploy services on a serverless, container-based platform.
• Build and improve CI/CD pipelines covering testing, validation, release automation, and deployment.
• Support production through monitoring, incident triage, root-cause analysis, and payment status reconciliation.
• Contribute to platform and edge improvements and to technical documentation.
• Collaborate with platform teams and external provider contacts.

Required Skills

• Strong backend experience in Kotlin (or Java with a readiness to work in Kotlin) and a modern framework such as Micronaut or Spring Boot.
• Hands-on experience with Google Cloud Platform (serverless compute, messaging, load balancing, security, secret management).
• Experience designing and consuming REST APIs and OpenAPI specifications, and working with API gateways.
• Solid understanding of webhook and callback patterns, idempotency, retries, and failure handling.
• Working knowledge of encryption and secure data exchange.
• Infrastructure as Code with Terraform.
• CI/CD with GitHub Actions or an equivalent tool.
• Strong testing discipline (unit, integration, contract) and observability practices.

Nice to Have

• Experience in payments or fintech, including PSP integrations, reconciliation, and PCI-DSS awareness.
• Knowledge of CDN and edge security (WAF, routing, security rules).
• Frontend skills (TypeScript, React or similar) for payment, redirect, or status-handling flows and internal tooling.
• Familiarity with regional payment methods and regulatory guidelines.
• Experience with event-driven architectures and microservices.
• Experience with monitoring tools such as Dynatrace, Splunk, Prometheus, or Grafana.