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

Note: The job is a remote job and is open to candidates in USA. Weekday AI (YC W21) is recruiting for a client that is a leading AI research organization focused on generative AI and advanced Large Language Models. The Senior Full Stack Software Engineer will build, integrate, test, and stress-test production-quality software interacting with frontier AI models, while collaborating with engineering and research teams in a fast-moving environment.

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 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
• 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
• Experience working with AI/ML systems, LLM APIs, AI coding tools, or model evaluation workflows is advantageous

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