Agentic Software Engineer (OpenAI Codex) - Remote - USA

FullStack is one of the fastest-growing software consultancy companies in the Americas, delivering transformational digital solutions to top global companies and Silicon Valley startups. They are seeking an Agentic Software Engineer focused on OpenAI Codex to integrate into client teams or work on FullStack product teams, leveraging AI-driven development to create high-quality software solutions.

Responsibilities:

• Integrate directly into our client's team and work alongside their existing designers and engineers daily
• Work on a FullStack product team to build and deliver a product to our clients
• Deep experience using OpenAI Codex as a primary development environment to coordinate AI-driven implementation across large, multi-file systems while maintaining architectural oversight
• Experience delivering production software where AI systems generate the majority of implementation code
• Strong context engineering skills, including structuring codebases, specifications, and documentation to produce reliable, context-efficient AI output
• Ability to translate complex product requirements into machine-executable, AI-friendly specifications
• Experience designing AI-first development workflows from specification through deployment
• Ability to systematically improve AI-generated output through structured iteration and feedback loops
• Comfort working across multiple stacks, using AI to deliver high-quality, production-ready systems
• Experience operating across frontend, backend, and infrastructure in AI-accelerated environments
• Disciplined human-in-the-loop review practices, with risk-adjusted validation for high-impact or safety-critical flows
• Strong curiosity and initiative in evaluating and adopting emerging AI-native engineering practices
• Advanced understanding of Agile methodologies and Lean principles and participation in team ceremonies as well as asynchronous work
• Ability to work through new and difficult issues and contribute to libraries as needed
• Ability to create and maintain continuous integration and delivery of applications
• Forensic attention to detail
• A positive mindset and a can-do attitude
• Experience working on Agile / Scrum teams
• Meaningful experience working on large, complex systems
• Ability to take extreme ownership over your work. Every day is a challenge to ensure you are performing to the expectations you and your team have agreed upon
• Ability to identify with the goals of FullStack's clients, and dedicate yourself to delivering on the commitments you and your team make to them
• Ability to consistently work 40 hours per week

Requirements:

• 5+ years of professional software development experience with a deep understanding of full-stack architectures (e.g., Java, Python, C#, React, Node, etc.)
• Advanced English is required
• Successful completion of a four-year college degree is required
• Deep experience using OpenAI Codex as a primary development environment to coordinate AI-driven implementation across large, multi-file systems while maintaining architectural oversight
• Experience delivering production software where AI systems generate the majority of implementation code
• Strong context engineering skills, including structuring codebases, specifications, and documentation to produce reliable, context-efficient AI output
• Ability to translate complex product requirements into machine-executable, AI-friendly specifications
• Experience designing AI-first development workflows from specification through deployment
• Ability to systematically improve AI-generated output through structured iteration and feedback loops
• Comfort working across multiple stacks, using AI to deliver high-quality, production-ready systems
• Experience operating across frontend, backend, and infrastructure in AI-accelerated environments
• Disciplined human-in-the-loop review practices, with risk-adjusted validation for high-impact or safety-critical flows
• Strong curiosity and initiative in evaluating and adopting emerging AI-native engineering practices
• Advanced understanding of Agile methodologies and Lean principles and participation in team ceremonies as well as asynchronous work
• Ability to work through new and difficult issues and contribute to libraries as needed
• Ability to create and maintain continuous integration and delivery of applications
• Forensic attention to detail
• A positive mindset and a can-do attitude
• Experience working on Agile / Scrum teams
• Meaningful experience working on large, complex systems
• Ability to take extreme ownership over your work. Every day is a challenge to ensure you are performing to the expectations you and your team have agreed upon
• Ability to identify with the goals of FullStack's clients, and dedicate yourself to delivering on the commitments you and your team make to them
• Ability to consistently work 40 hours per week