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

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

This role is for one of our clients

Compensation: $90-$110 per hour

Join a leading AI research organization at the forefront of generative AI and contribute to the development and evaluation of advanced Large Language Models. We are seeking experienced Senior Full-Stack Software Engineers with strong production expertise across modern software ecosystems, including Python, Java, Rust, C#, C++, and TypeScript.

In this role, you will build, integrate, and stress-test production-quality software that interacts with frontier AI models. You will work closely with engineering and research teams on fast-moving initiatives, rapidly adapt to new codebases and requirements, and contribute working code early in the engagement.

This is a full-time role requiring 40 hours per week.

Requirements

2. Key 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.

3. Core Qualifications

• 6+ years of professional software engineering experience building and shipping production systems at established technology organizations or comparable environments.
• Strong hands-on production expertise in at least one of Python, Java, Rust, C#, or C++, along with meaningful professional experience delivering software in a second programming language or ecosystem.
• 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.

4. What Success Looks Like

The successful candidate will be able to quickly become productive within unfamiliar technical environments, independently solve complex engineering problems, and deliver reliable software that helps teams evaluate and advance frontier AI capabilities.

You should be comfortable operating in a fast-moving environment where requirements evolve quickly, technical ambiguity is common, and high-quality working code is valued over lengthy upfront planning.

5. Equal Opportunity

We are committed to providing equal employment opportunities to all qualified applicants. We do not discriminate based on legally protected characteristics and provide reasonable accommodations to qualified individuals throughout the application and engagement process.

6. Role Details

• Role: Senior Software Engineer, Full Stack
• Specializations: Python, Java, Rust, C#, C++, TypeScript
• Employment Type: Full-Time
• Work Commitment: 40 hours per week
• Focus: Full-stack development, AI model integration, software evaluation, testing, debugging, and production engineering