At a Glance
- Tasks: Design and build execution environments for AI agents, optimising performance and reliability.
- Company: Join OpenAI, a leader in AI research and deployment with a mission to benefit humanity.
- Benefits: Competitive salary, inclusive culture, and opportunities for professional growth.
- Other info: Dynamic team environment with a focus on innovation and collaboration.
- Why this job: Be at the forefront of AI technology, making a real impact on the future.
- Qualifications: Experience in distributed systems, infrastructure engineering, and a passion for reliability.
The predicted salary is between 72000 - 88000 £ per year.
About the Team
The Codex Core Agent team builds the kernel of Codex. We own making the agent better, accelerating research, and making those improvements real in production for our users. That means working across the systems that make Codex actually function as an agent in the real world: the production performance envelope around tokens, latency, reliability, cost, and capacity; the core execution loop and interfaces that turn models into useful behaviour; the shared infrastructure that enables other teams to build on Codex; and the feedback loops that turn real-world usage into better models and better agent behaviour over time.
About the Role
We're looking for engineers to build the infrastructure that powers Codex agents in production. This role focuses on the systems that let models safely execute code, interact with tools, complete long-running tasks, and operate reliably and efficiently at scale. You'll design and operate the infrastructure behind sandboxed execution, orchestration, stateful workflows, app-server and SDK boundaries, and model rollouts. You'll work at the intersection of distributed systems, developer tooling, and AI, building primitives that make Codex faster, safer, more reliable, and easier for the rest of the organisation to build on.
What You'll Do
- Design and build execution environments for AI agents, including sandboxing, isolation, and reproducibility.
- Develop systems for agent orchestration across multi-step, tool-using workflows.
- Build infrastructure for running, testing, and debugging code generated by models.
- Create state and memory systems that allow agents to persist context across long-running tasks.
- Optimize tokens, latency, reliability, and cost across Codex’s production fleet.
- Support model rollouts, capacity planning, and the core tradeoffs between quality, speed, and economics to manage a fleet of frontier agents at scale.
- Build shared platform capabilities that unblock product teams, partner teams, and open source Codex.
You Might Be a Good Fit If You
- Have strong experience in distributed systems or infrastructure engineering.
- Have built systems involving containers, sandboxing, or virtualization.
- Are comfortable working across backend systems, APIs, and developer tooling.
- Care deeply about system reliability, performance, and security.
- Enjoy working on ambiguous, zero-to-one problems.
- Want to help build the systems that turn model capability into a dependable software engineering agent.
Bonus Points
- Experience with code execution platforms, CI/CD systems, or build systems.
- Experience coding in Rust.
- Familiarity with LLMs, agents, or tool-use frameworks.
- Background in security engineering or isolation systems.
- Experience building developer platforms, IDE tooling, or open source infrastructure.
About OpenAI
OpenAI is an AI research and deployment company dedicated to ensuring that general-purpose artificial intelligence benefits all of humanity. We push the boundaries of the capabilities of AI systems and seek to safely deploy them to the world through our products. AI is an extremely powerful tool that must be created with safety and human needs at its core, and to achieve our mission, we must encompass and value the many different perspectives, voices, and experiences that form the full spectrum of humanity.
We are an equal opportunity employer, and we do not discriminate on the basis of race, religion, colour, national origin, sex, sexual orientation, age, veteran status, disability, genetic information, or other applicable legally protected characteristic.
We are committed to providing reasonable accommodations to applicants with disabilities, and requests can be made via this link.
At OpenAI, we believe artificial intelligence has the potential to help people solve immense global challenges, and we want the upside of AI to be widely shared. Join us in shaping the future of technology.
Software Engineer, Codex Core Agents in City of London employer: OpenAI
OpenAI is an exceptional employer, offering a unique opportunity to work at the forefront of AI technology while collaborating with leading organizations to create impactful solutions. With a hybrid work model and a strong commitment to employee growth, OpenAI fosters a culture of innovation and inclusivity, ensuring that every team member can contribute to meaningful projects that benefit humanity. The company's focus on safety, diverse perspectives, and professional development makes it an attractive place for those seeking a rewarding career in applied AI engineering.
StudySmarter Expert Advice🤫
We think this is how you could land Software Engineer, Codex Core Agents in City of London
✨Join Local Tech Meetups
Get out there and mingle with fellow developers by joining local tech meetups. It’s a fantastic way to meet people who might be working at OpenAI or know someone who does. Plus, you can pick up some trendy tech skills and trends while you're at it!
✨Contribute to Open Source Projects
Show off your coding chops by jumping into open-source projects. Not only does this give you practical experience, but it also gets you noticed in the dev community. You'll create a killer portfolio that speaks volumes about your skills to OpenAI.
✨Tap into Online Developer Communities
Don’t underestimate the power of online developer communities like GitHub, Stack Overflow, and even Reddit. Participate in discussions, share your projects, and build your visibility. We can often find opportunities through these channels that can lead to a full-time gig at companies like OpenAI.
✨Explore Job Boards Specifically for Tech Roles
Keep your eyes peeled on job boards that focus on tech roles. Sites like TechCareers or Stack Overflow Jobs can often have listings for companies like OpenAI that might not show up on broader job sites. Make it a habit to check these regularly, and don’t hesitate to apply directly through our website!
We think you need these skills to ace Software Engineer, Codex Core Agents in City of London
Some tips for your application 🫡
Show off your coding skills:When applying for a software engineering role, it's super important to showcase your coding skills. Make sure your CV includes your tech stack, any relevant programming languages you’re comfortable with, and examples of projects you've worked on. If you have a GitHub profile, link it up! We love to see code in action.
Tailor your portfolio:For a full-time role, we’d expect to see some solid examples of your work in your portfolio. Make sure to include at least two or three projects that highlight your problem-solving skills and your ability to work with different technologies. Focus on the projects that are most relevant to the position at OpenAI.
Craft a killer cover letter:Your cover letter is your chance to stand out—make it personal! Explain why you want to work at OpenAI and how your skills align with the role. Show us your passion for software development. We dig enthusiastic candidates who understand the value of collaboration and continuous learning!
Be clear and concise:When it comes to writing your CV and cover letter, clarity is key. Avoid jargon that could confuse us and stick to simple, direct language. Highlight your achievements with quantifiable results where possible, and keep everything easy to read. A well-organised application goes a long way!
How to prepare for a job interview at OpenAI
✨Brush Up on Your Coding Skills
For a full-time software engineering role, it's crucial that we stay sharp with our coding abilities. Expect technical questions that might involve solving problems on the spot or discussing algorithms. Practise on platforms like LeetCode or HackerRank to get comfortable with the types of questions that often come up.
✨Know Your Tools and Frameworks
Make sure we’re well-acquainted with the tools and technologies listed in the job description. Familiarise ourselves with any specific frameworks or programming languages mentioned. If OpenAI uses React or Node.js, for instance, be ready to discuss how we’ve used them in previous projects or coursework.
✨Showcase Your Projects
Bring along a portfolio that highlights our best work. This could be code samples, GitHub repositories, or any side projects we’ve built. Make sure we can talk through our thought process for each project, especially the challenges we faced and how we solved them—this shows our problem-solving skills in action.
✨Prepare for Behavioural Questions
While technical skills are key, full-time positions also require cultural fit. Be ready to discuss our previous experiences and how we handle teamwork, conflict, and deadlines. Brush up on the STAR method—Situation, Task, Action, Result—to clearly articulate our past experiences when discussing how we've contributed to a team.
