Senior Software Engineer, Full Stack (Python, Java, Rust, C#, C++)

AI Trainer Jobs; United States; On-site; USD 140,000 - 180,000; Full time

Job summary

AI Trainer Jobs is seeking Senior Full-Stack Software Engineers to join a leading AI lab's GenAI team. You will build, integrate, and stress-test production software atop frontier models, using Python, Java, Rust, C#, C++, and TypeScript.

You will own backend services, APIs, and a modern frontend, with cloud deployment and telemetry. Expect to onboard quickly, ship working code early, and collaborate with the engineering manager on fast-moving projects.

Qualifications

• 6+ years of professional production software experience at a top-tier organization.
• Deep production expertise in Python, Java, Rust, C#, C++, plus delivery in a second language.
• Hands-on ownership across backend, APIs, frontend (React), data modeling, and cloud deployment.
• Able to onboard quickly and deliver working code with minimal ramp-up.
• Strong written communication to explain complex technical decisions.

Responsibilities

• Build and ship full-stack applications, services, and internal tools across Python, Java, Rust, C#, C++, or TypeScript.
• Integrate pre-release model APIs into working software, including scaffolding and telemetry.
• Diagnose and document model and integration failure modes surfaced during development.
• Prototype rapidly against shifting requirements with incremental delivery.
• Collaborate with the engineering manager and peers to maintain code quality and documentation.

Skills

Full-stack ownership

Strong communication

Onboarding to new codebase

Proactive problem solving

Education

Bachelor's degree in Computer Science

Tools

Python

Java

Rust

C++

C#

TypeScript

React

Cloud deployment (AWS/Azure)

Job description

Join a leading AI lab's cutting-edge GenAI team to be at the core of the AI revolution, where your expertise fuels the development of the most advanced Large Language Models.

Overview

Join a leading AI lab's cutting-edge GenAI team and help build foundational AI models from the ground up. We're seeking talented Senior Full-Stack Software Engineers with deep, hands‑on production expertise across modern application stacks — Python, Java, Rust, C#, C++, and TypeScript — to build, integrate, and stress‑test real software on top of frontier models before they ship. Engineers work directly with the AI lab's engineering manager on fast‑moving projects and are expected to onboard quickly and contribute working code early. This is a full‑time commitment of 40 hours per week.

This is a W‑2 employment position with Cincinnatus LLC, with the opportunity to be placed at a leading AI Lab as part of their extended workforce.

Key Responsibilities

Build and ship full‑stack applications, services, and internal tools — in Python, Java, Rust, C#, C++, or TypeScript — that exercise frontier model capabilities end to end.

Integrate pre‑release model APIs into working software, including the surrounding scaffolding: tool interfaces, evaluation harnesses, and telemetry.

Diagnose and document model and integration failure modes surfaced while building, translating engineering observations into clear written feedback for the research team.

Prototype quickly against shifting requirements, delivering working increments with limited up‑front specification.

Collaborate with the engineering manager and other engineers to maintain consistency in code quality, architecture, and technical documentation.

Core Qualifications

6+ years of dedicated professional experience building and shipping production software at a recognized, top‑tier organization, including ownership of systems end to end.

Deep production experience in at least one of Python, Java, Rust, C#, or C++, plus demonstrated delivery in a second language across a different ecosystem — this cohort is intentionally staffed across multiple language ecosystems.

Hands‑on ownership across the stack: backend service and API design, a modern front‑end framework (React or equivalent), data modelling, and cloud deployment and operations.

Demonstrated ability to onboard onto an unfamiliar codebase and deliver working code quickly with minimal ramp‑up.

Demonstrable career progression.

Ability to engage reliably for at least 40 hours/week during weekdays.

Strong written communication skills and the ability to explain complex technical decisions clearly.

About Cincinnatus LLC: Cincinnatus LLC is an enterprise staffing company that partners with leading technology companies to source and employ highly skilled professionals for contingent and contract‑based opportunities. Cincinnatus serves as the employer of record for these engagements, providing W‑2 employment, payroll, benefits, and compliance, while placing employees directly within client teams to work on high‑impact initiatives.

Equal Employment Opportunity: Cincinnatus is proud to be an Equal Employment Opportunity employer. We do not discriminate based upon race, religion, color, national origin, sex (including pregnancy, childbirth, reproductive health decisions, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, genetic information, political views or activity, or any other legally protected characteristic.

We consider all qualified applicants without regard to legally protected characteristics and provide reasonable accommodations upon request.