Senior Full-Stack Engineer, AI/LLM Integration

Weekday 1; United States; On-site; USD 124,000 - 152,000; Full time

Job summary

Weekday 1 is seeking a Senior Software Engineer, Full Stack, to join a leading AI research organization in the United States. You will design, develop, and stress-test production-quality software across Python, Java, Rust, C#, C++, and TypeScript, interfacing with frontier AI models.

In this role you will own end-to-end development, collaborate with research and engineering teams, and translate evolving requirements into high-quality, deployable code while maintaining strong standards for

Qualifications

• 6+ years of professional software engineering experience building and shipping production systems.
• Strong hands-on production expertise in at least one of Python, Java, Rust, C#, or C++.
• Demonstrated full-stack engineering experience covering: Backend services and API development, Modern frontend frameworks such as React or equivalent, Database and data-model design, Cloud infrastructure and deployment, Production operations and system reliability.
• Experience owning software systems end to end, from design and implementation through deployment, monitoring, debugging, and ongoing improvement.
• Ability to quickly understand unfamiliar architectures, repositories, development environments, and technical requirements, then begin delivering production-quality code with minimal ramp-up.
• Demonstrated career progression and increasing technical ownership throughout your engineering career.
• Strong understanding of software engineering best practices, including testing, version control, code review, debugging, system design, and technical documentation.
• Experience working with AI/ML systems, LLM APIs, AI coding tools, or model evaluation workflows is advantageous.
• Strong written and verbal communication skills, with the ability to clearly explain technical decisions, trade-offs, implementation details, and system behavior.
• Ability to commit reliably to 40 hours per week during weekdays.

Responsibilities

• Build full-stack applications: Design, develop, and ship production-quality applications, backend services, APIs, and internal tools using technologies such as Python, Java, Rust, C#, C++, and TypeScript.
• Integrate AI models: Integrate pre-release and frontier model APIs into functional software systems, including tool interfaces, evaluation frameworks, telemetry, and supporting infrastructure.
• Develop across the stack: Work across backend services, APIs, databases, frontend applications, cloud infrastructure, and deployment environments to deliver complete solutions.
• Test and stress-test systems: Build applications and testing frameworks that exercise model capabilities and identify performance, reliability, integration, and usability issues.
• Identify failure modes: Diagnose technical and model-related failures encountered during development and document findings clearly for engineering and research teams.
• Prototype rapidly: Translate evolving requirements into working software, delivering high-quality iterations with limited upfront specifications.
• Collaborate with engineering teams: Partner with engineering managers and fellow developers to maintain strong standards for architecture, code quality, testing, documentation, and maintainability.

Skills

6+ years

Full-stack

Python

Java

Rust

C#

C++

TypeScript

React

SQL

Docker

Kubernetes

LLM APIs

Tools

React

SQL/Databases

Docker

Kubernetes

LLM APIs

Job description

Weekday 1 is seeking a Senior Software Engineer, Full Stack, to join a leading AI research organization in the United States. You will design, develop, and stress-test production-quality software across Python, Java, Rust, C#, C++, and TypeScript, interfacing with frontier AI models.

In this role you will own end-to-end development, collaborate with research and engineering teams, and translate evolving requirements into high-quality, deployable code while maintaining strong standards for