Senior Backend Engineer Kotlin / Spring Boot / Temporal Workflow

Requisition ID: 107871-1
Title: Senior Backend Engineer Kotlin / Spring Boot / Temporal Workflow
Location: Phoenix, AZ (Need only Phoenix local candidate)
Duration: 6+ Months
Salary Range: $40- $45 an hour on W2 /C2C

We are seeking a Senior Backend Engineer with 8+ years of software engineering experience and strong hands-on expertise in Kotlin/JVM, Spring Boot, distributed systems, and workflow orchestration. The ideal candidate will have production experience building scalable backend services and durable workflow platforms, with Temporal.io experience strongly preferred.

The engineer will design, develop, and maintain resilient backend services and workflow runtime components supporting long-running, asynchronous, and distributed business processes.

Key Responsibilities

Backend & Runtime Engineering

• Design, develop, and maintain scalable Kotlin/Spring Boot backend services and workflow runtime components.
• Build REST APIs and platform services supporting long-running, asynchronous, and distributed workflows.
• Implement reliable execution patterns including idempotency, retries, timeouts, compensation, failure recovery, and safe reprocessing.
• Develop event-driven integrations using Kafka and REST APIs.
• Apply microservices and distributed-systems design principles to build reliable, scalable services.

Workflow Orchestration

• Design and implement durable workflows using Temporal.io, including Workflows, Activities, Signals, and Queries.
• Ensure workflow implementations are deterministic and replay-safe.
• Design workflow versioning strategies to support workflows running across multiple software releases.
• Build reusable workflow components, execution controls, state management, and operational tooling.
• Troubleshoot workflow failures and improve runtime resiliency, observability, recoverability, and operational reliability.
• Experience with AWS Step Functions, Camunda, Airflow, or similar orchestration platforms is a plus.

Platform, Data & Cloud

• Integrate workflow and backend services with PostgreSQL, NoSQL databases, and enterprise APIs.
• Develop applications using strong SQL, JPA/Hibernate, and data-access patterns.
• Containerize and deploy services using Docker and Kubernetes.
• Work with AWS, GCP, or Azure cloud environments.
• Build and maintain CI/CD pipelines using tools such as GitHub Actions or Jenkins.
• Implement production observability using Splunk, Grafana, Prometheus, ELK, or equivalent technologies.
• Support logging, metrics, distributed tracing, dashboards, and alerting.

Testing & Engineering Quality

• Develop unit, integration, and automated tests using JUnit and Mockito.
• Implement container-based integration testing using Testcontainers or equivalent.
• Follow API-first and contract-first development practices.
• Participate in code reviews, architecture reviews, and technical design discussions.
• Maintain high standards for clean code, security, reliability, scalability, and maintainability.

Engineering Leadership

• Own software delivery from technical design through production support.
• Mentor engineers and provide technical guidance on backend and distributed-system development.
• Collaborate with Product, Architecture, QA, DevOps, and Platform teams.
• Troubleshoot complex production issues and drive root-cause analysis and resolution.
• Work effectively in an Agile environment and independently drive technical initiatives.

AI / Modern Engineering Preferred

• Exposure to LLM/AI application runtimes, AI agents, RAG, tool calling, LangChain, or LangGraph is a plus.
• Experience integrating AI-driven workloads into reliable and secure enterprise backend platforms is preferred.
• Knowledge of using durable workflow execution for AI agents, tool invocation, and human-in-the-loop processes is advantageous.

Required Skills

• 8+ years of software engineering experience with strong hands-on backend development.
• Strong production experience with Kotlin/JVM and Spring Boot.
• Strong Kotlin knowledge including:
  • Coroutines
  • Null safety
  • Collections
  • Functional programming
  • Java interoperability
• Strong Java fundamentals and modern JVM application development.
• Strong experience with Spring Boot, Spring Framework, Spring Data JPA/Hibernate, and REST APIs.
• Strong knowledge of microservices and distributed systems.
• Strong understanding of concurrency, asynchronous processing, idempotency, retries, timeouts, failure handling, and resilient service design.
• Temporal.io experience is highly preferred, including:
  • Temporal Workflows
  • Activities
  • Signals
  • Queries
  • Durable execution
  • Workflow state management
  • Replay-safe/deterministic execution
  • Workflow versioning
  • Long-running processes
  • Failure recovery
• Experience with Kafka or equivalent messaging platforms.
• Strong PostgreSQL and SQL skills.
• Exposure to MongoDB, Redis, or other NoSQL technologies.
• Experience with Docker, Kubernetes, and CI/CD.
• Experience with at least one cloud platform: AWS, Azure, or GCP.
• Experience with GitHub Actions or Jenkins.
• Experience with observability tools such as Splunk, Grafana, Prometheus, or ELK.
• Strong experience with JUnit, Mockito, and integration testing.
• Excellent communication, troubleshooting, collaboration, and technical leadership skills.

Preferred Skills

• Terraform
• Testcontainers
• Contract testing / contract-first API development
• AWS Step Functions
• Camunda
• Airflow
• MongoDB / Redis
• AI Agents / LLM
• RAG
• LangChain / LangGraph
• Human-in-the-loop AI workflows