Backend Software Engineer - GenAI

Mosaic.tech; New York (NY); On-site; USD 140,000 - 190,000; Full time

Benefits offered by this job

Health insurance

401(k) plan

Commuter benefits

On-site gym

Job summary

Rune Technologies is building the logistics technology backbone for the U.S. and allied militaries.

As a Backend Software Engineer focusing on Saga, you will own the design and implementation of production GenAI systems that bring intelligent, autonomous capabilities to the sustainment domain. This role emphasizes backend engineering first, collaborating with engineers, product designers, and military stakeholders to ship reliable software for real-world use, including integration with TyrOS and

Qualifications

• 4+ years of software engineering experience with backend and distributed systems.
• Hands-on GenAI systems experience with vector databases and LLMs.
• Experience with tool routing and LLM failure modes.
• Background at an AI-native company, or a clear transition from backend engineering into AI specialization.
• Strong sense of ownership and bias for action.

Responsibilities

• Design, build, and deploy production-grade GenAI systems — including RAG architectures, vector databases, LLM integrations, and tool-call frameworks — in support of Saga, Rune’s AI agentic product layer.
• Build and maintain evaluation and testing harnesses to validate LLM output quality and catch regressions in production.
• Collaborate with the broader platform and product teams to integrate AI capabilities into TyrOS workflows.
• Participate in technical design discussions and code reviews, contributing to a culture of engineering rigor and mission focus.
• Triage and debug issues in production, ensuring reliability and rapid iteration in support of operational needs.
• Work closely with engineers, product managers, and military stakeholders to ensure AI systems meet real-world sustainment requirements.

Skills

Backend engineering

GenAI systems

LLM integration

RAG architectures

Vector databases

Tool routing

Tools

AWS

Kubernetes

Job description

About Rune

Rune Technologies builds mission-critical software for military logistics and sustainment. Our flagship product is TyrOS, an AI-enabled logistics command and control platform that gives commanders a single, real-time operating picture of their sustainment fight, from inventory and distribution to medical and operational planning, even in degraded and contested environments.

We’re not a traditional defense contractor. We’re a small, fast-moving team that combines deep operational experience in and with the DoD with the software discipline of the best product companies, and we apply that combination to a customer set that desperately needs it. We stay close to our users by embedding directly with military units during exercises and rotations, and we ship constantly based on what we learn.

The U.S. military and its allies face a real logistics modernization problem. We’re building the software to solve it.

About the Role

At Rune Technologies, we are building the logistics technology backbone that the U.S. and allied militaries need to dominate in large-scale combat operations. As a Backend Software Engineer at Rune, you will be part of a high-impact team working at the intersection of advanced logistics algorithms, modern AI enabled software, and complex system integrations — all in support of the warfighter at the tactical edge. You’ll join us in our mission to bring 21st-century software to the sustainment domain — modernizing inventory management, transportation optimization, and predictive maintenance with state-of-the-art user experiences. You’ll work closely with a team of experienced engineers, product designers, and operational experts who care deeply about delivering real-world impact.

As a Backend Software Engineer focused on Saga — Rune’s AI agentic layer within TyrOS — you will own the design and implementation of production GenAI systems that bring intelligent, autonomous capability to the sustainment domain. This is a backend engineering role first: we’re looking for someone who has built real AI systems from the ground up, worked closely with engineers and operational experts, and cares about shipping software that actually works in the field.

What You’ll Do

• Design, build, and deploy production‑grade GenAI systems — including RAG architectures, vector databases, LLM integrations, and tool‑call frameworks — in support of Saga, Rune’s AI agentic product layer.

• Build and maintain evaluation and testing harnesses to validate LLM output quality and catch regressions in production.

• Collaborate with the broader platform and product teams to integrate AI capabilities into TyrOS workflows.

• Participate in technical design discussions and code reviews, contributing to a culture of engineering rigor and mission focus.

• Triage and debug issues in production, ensuring reliability and rapid iteration in support of operational needs.

• Work closely with engineers, product managers, and military stakeholders to ensure AI systems meet real‑world sustainment requirements.

Qualifications

• 4+ years of experience in software engineering, with a strong backend foundation — distributed systems, APIs, production‑grade software.

• Hands‑on experience building GenAI systems: vector databases, LLM integration, RAG architectures, and evaluation harnesses for LLM output.

• Familiarity with tool routing, tool‑call validation, and common LLM failure modes.

• Understanding of the science underlying the systems you build — not just how to wire them together, but why they work and where they break.

• Background at an AI‑native company, or a clear transition from backend engineering into AI specialization.

• Strong sense of ownership and a bias for action.

Desired Qualifications

• Experience with fine‑tuning or model evaluation workflows.

• Familiarity with AI infrastructure: embedding pipelines and inference optimization.

• Experience working on software in defense, aerospace, or other complex operational domains.

• Experience deploying software to production environments, including cloud (AWS, Kubernetes) and edge infrastructure.

Benefits

Rune offers top‑tier benefits for full‑time employees to include a full suite of insurance options at no cost for employees and low‑cost to spouses and dependents. Highly competitive equity grants are also included in the majority of full‑time offers and are considered part of Rune's total compensation package. Benefits include:

• Comprehensive medical, dental, and vision plans; premiums 100% covered by Rune for all employees; exceptionally low premiums for spouses and dependents

• Basic life insurance and disability 100% covered for all employees by Rune; option to purchase additional life insurance available

• ‘Take the time off that you need, when you need it’ paid time off, not accrual based

• Generous company holiday calendar including a holiday shutdown in December

• Supportive leave of absence program including time off for military service, medical events, and parental leave

• Full 401(k) retirement plan for all full‑time eligible employees

• Company‑funded commuter benefits

• Free access to on‑site gym at office