Kotlin Developer

JOB DESCRIPTION: We’re hiring a senior Kotlin/Spring Boot contractor to help own the execution backbone of a no-code workflow platform. This is not a simple CRUD service. The Orchestrator runtime is a multi-module system that receives workflow execution requests, persists durable state with Temporal, coordinates graph execution, integrates HTTP, agent, LLM, and human-review nodes, and safely executes increasingly AI-generated workflow graphs. You’ll join the squad responsible for the runtime layer that everything else depends on. Responsibilities: Design and harden the Kotlin/Spring Boot runtime that executes workflow graphs reliably in production. Implement and improve Durable Execution Solutions 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. 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 Strong Pluses: Experience with DAG/workflow/orchestration engines. Experience with AI/LLM/agent runtimes or other non-deterministic execution systems. Familiarity with FastAPI-based workers and cross-language integration. Experience with auth/token provider abstractions, OAuth2/JWT, or cached token acquisition. Experience writing operational docs, runbooks, and reliability guidance. Show more Show less