Senior Kotlin Engineer

Aptimized; Phoenix (AZ); On-site; USD 140,000 - 200,000; Full time

Job summary

Aptimized is seeking a Senior Backend Engineer to join our fast-paced Payments team focused on digital wallet platforms and API integrations with major providers such as Apple Pay, Google Pay, and Samsung Wallet. You will contribute to the development of highly scalable, secure, cloud-native backend services supporting wallet orchestration, tokenization, banking integrations, and payment processing.

The role requires strong Java and Kotlin experience, microservices, Kafka, and OpenShift in a

Qualifications

• Strong backend experience with Java (8+), Kotlin for enterprise apps.
• Proven microservices architecture and cloud-native development.
• Experience with Kafka for asynchronous processing.
• Proficiency with REST APIs and API security.
• Experience with NoSQL databases (Couchbase).
• Familiarity with OpenShift or similar orchestration.

Responsibilities

• Design and develop backend microservices for payment and wallet ecosystems.
• Build secure public APIs and integration services.
• Implement asynchronous processing with Kafka.
• Integrate with wallet providers and financial institutions.
• Ensure security, tokenization and encryption.
• Work in OpenShift-based cloud environment.
• Collaborate with cross-functional teams.

Skills

Java 8+

Java 21+

Kotlin

Microservices

Vert.x

Spring Boot

Kafka

NoSQL Couchbase

REST APIs

API security

Encryption/Crypto

Cloud-native

OpenShift

Tools

OpenShift

Job description

We are seeking a Senior Backend Engineer to join a fast-paced Payments team focused on digital wallet platforms and API integrations with major providers such as Apple Pay, Google Pay, and Samsung Wallet. The engineer will contribute to the development of highly scalable, secure, cloud-native backend services supporting wallet orchestration, tokenization, banking integrations, and payment processing.

Key Responsibilities

• Design and develop backend microservices for payment and wallet ecosystems.
• Build and maintain secure public-facing APIs and integration services.
• Develop asynchronous and event-driven solutions using Kafka and related messaging technologies.
• Implement integrations with digital wallet providers and financial institutions.
• Contribute to tokenization, data security, encryption, and authentication solutions.
• Work within a cloud-native environment deployed on OpenShift.
• Collaborate with cross-functional teams to deliver highly available and scalable services.

Required Qualifications

• Strong experience with Java (Java 8+ required, Java 21 preferred).
• Experience with Kotlin in enterprise backend applications.
• Hands-on experience building microservices architectures.
• Experience with Vert.x (preferred) or similar reactive frameworks.
• Strong understanding of Spring Boot.
• Experience with Kafka and asynchronous processing patterns.
• Experience with NoSQL databases, preferably Couchbase.
• Strong understanding of REST APIs and API security.
• Knowledge of encryption, token signing, symmetric and asymmetric cryptography.
• Experience working in cloud-native and containerized environments.
• Familiarity with OpenShift or similar orchestration platforms.

Preferred Qualifications

• Experience in Payments, FinTech, Digital Wallets, or Banking domains.
• Knowledge of tokenization solutions and sensitive data protection.
• Experience with JEE.
• Experience with reactive programming and advanced concurrency concepts.
• Familiarity with virtual threads, CompletableFuture, and modern Java asynchronous patterns.
• Exposure to AI/OpenAI-enabled solutions.

Nice to Have

• Experience integrating Apple Pay, Google Pay, Samsung Wallet, or similar payment platforms.
• Experience with large-scale payment processing systems.