Senior Kotlin Backend Engineer: Spring Boot + Temporal

Santex; United States; Remote; USD 96,000 - 165,000; Part time

Job summary

Santex is hiring a senior Kotlin/Spring Boot contractor to own the execution backbone of a no-code workflow platform. The Orchestrator runtime handles workflow execution, persistence with Temporal, and integration across HTTP, agent, LLM, and human-review nodes.

This role sits in the runtime layer that other components depend on. The candidate will design robust Kotlin/Spring Boot services, implement Temporal workflows, and ensure durable, recoverable executions within a multi-module, API-first

Qualifications

• Strong production Kotlin backend experience.
• Strong Spring Boot experience in distributed systems or platform services.
• Hands-on Temporal experience in production.
• Strong understanding of workflow durability, retries, idempotency, and recovery design.
• Experience with multi-module Gradle codebases and contract-first API design.
• Experience with JPA/Hibernate and PostgreSQL.
• Experience with Docker Compose/Test containers integration testing.
• Comfort debugging multi-service systems with mixed Kotlin and Python components.
• Experience with observability tools like micrometer
• Experience with contract first development
• Advanced English is required for this position.

Responsibilities

• Design and harden the Kotlin/Spring Boot runtime that executes workflow graphs reliably in production.
• Implement and improve Temporal.io workflows, activities, signals, queries, retries, and recovery paths.
• Strengthen contract-first APIs and shared contracts.
• Own failure-mode thinking across distributed execution retries, idempotency, partial failure, replay safety, pause/resume, and graceful degradation.
• Work across node types, including HTTP, agentic tool-calling, LLM, and human-in-the-loop review nodes.
• Improve integration coverage using Test containers and layered Docker Compose profiles.
• Collaborate closely with Composer and AI/KB teams on execution semantics and runtime behavior.
• Write clear operational documentation and runbooks for a reliability-critical service.

Skills

Kotlin backend

Spring Boot

Temporal

Distributed systems

PostgreSQL

Docker Compose

Micrometer

API design

English

Tools

Gradle

JPA/Hibernate

Docker

Test containers

Python

OAuth2/JWT

Job description

Santex is hiring a senior Kotlin/Spring Boot contractor to own the execution backbone of a no-code workflow platform. The Orchestrator runtime handles workflow execution, persistence with Temporal, and integration across HTTP, agent, LLM, and human-review nodes.

This role sits in the runtime layer that other components depend on. The candidate will design robust Kotlin/Spring Boot services, implement Temporal workflows, and ensure durable, recoverable executions within a multi-module, API-first