Senior Software Engineer - Full-Stack, Kotlin & AI-Driven

Mosaec; Minneapolis, Northern (MN, KY); Hybrid; USD 140,000 - 190,000; Full time

Job summary

Collaboration.Ai, headquartered in Minneapolis, Minnesota, builds AI-powered software for defense and regulated industries. You’ll own full-stack development across Kotlin/Spring Boot microservices and Next.js/React interfaces, with frequent production releases on a small, senior team.

This is hands-on ownership from database schema to UI, with no cross-team handoffs. You’ll design scalable APIs, optimize data access, and implement reliable, scalable systems that support growth while meeting

Qualifications

• 5+ years of professional software engineering experience, backend-focused with frontend contributions.
• Strong Kotlin and Spring Boot expertise; Java/Spring acceptable with Kotlin willingness.
• Proficiency in TypeScript and React, able to ship UI features within an established design system.
• Experience with Python and modern frameworks (FastAPI preferred).
• Hands-on Docker, Kubernetes, AWS; understanding of microservices and API design.
• US citizenship required for DoD contracting and FedRAMP compliance.

Responsibilities

• Deliver features end-to-end—from PostgreSQL schema to Kotlin service and Next.js UI.
• Own core API and service health with GraphQL/REST APIs.
• Design PostgreSQL schemas and manage migrations.
• Maintain CI/CD with quality gates and test coverage.
• Build resilient systems with logging, tracing, metrics and circuit breakers.
• Mentor mid-level and junior engineers through reviews and discussions.
• Automate with AI-native tooling to accelerate development.

Skills

Kotlin

Spring Boot

TypeScript

React

Python

PostgreSQL

Docker

Kubernetes

AWS

AI-native workflows

Tools

GitHub Actions

Liquibase

Job description

Collaboration.Ai, headquartered in Minneapolis, Minnesota, builds AI-powered software for defense and regulated industries. You’ll own full-stack development across Kotlin/Spring Boot microservices and Next.js/React interfaces, with frequent production releases on a small, senior team.

This is hands-on ownership from database schema to UI, with no cross-team handoffs. You’ll design scalable APIs, optimize data access, and implement reliable, scalable systems that support growth while meeting