Backend Engineer - API

xai· Engineering
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📍 London, UK

About this role

ABOUT xAI

xAI’s mission is to create AI systems that can accurately understand the universe and aid humanity in its pursuit of knowledge. Our team is small, highly motivated, and focused on engineering excellence. This organization is for individuals who appreciate challenging themselves and thrive on curiosity. We operate with a flat organizational structure. All employees are expected to be hands-on and to contribute directly to the company’s mission. Leadership is given to those who show initiative and consistently deliver excellence. Work ethic and strong prioritization skills are important. All employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates.

ABOUT THE ROLE:

As an ideal candidate you have a good understanding of how highly scalable and reliable production infrastructure is built. Most of our backend infrastructure is written in Rust. So familiarity with a compiled language such as C++, Rust, or Go is highly beneficial.

RESPONSIBILITIES:

  • Build the xAI API that serves our models to developers worldwide
  • Own the end-to-end system responsible for high-throughput inference, handling billions of tokens per minute with low latency and high availability, including model serving infrastructure, request routing, SDK development, rate limiting, observability, and efficient scaling

BASIC QUALIFICATIONS:

  • Expert knowledge of either Rust or C++
  • Experience in designing, implementing, and maintaining reliable and horizontally scalable distributed systems
  • Knowledge of service observability and reliability best practices
  • Experience in operating commonly used databases such as PostgreSQL, Clickhouse, and MongoDB

PREFERRED SKILLS AND EXPERIENCE:

  • Experience with LLM inference engines and serving frameworks (e.g., SGLang, TensorRT, vLLM)
  • Experience designing or building with agent SDKs and agent orchestration frameworks
  • Experience with Docker, Kubernetes, and containerized applications
  • Expert knowledge of gRPC (unary, response streaming, bi-directional streaming, REST mapping)

COMPENSATION AND BENEFITS:

£107,000 - £262,000 GBP

Base salary is just one part of our total rewards package at xAI, which also includes equity, comprehensive healthcare and dental coverage, cash plan, income protection, life insurance, and various other discounts and perks.

xAI is an equal opportunity employer. For details on data processing, view our Recruitment Privacy Notice.

Frequently Asked Questions

Is the salary disclosed for the Backend Engineer - API position at xai?
The salary for this Backend Engineer - API role at xai is not publicly listed. Click "Apply Now" to learn more about the compensation package on their official careers page.
Where is the Backend Engineer - API position at xai located?
This Backend Engineer - API role at xai is based in London, UK. The position is listed as on-site or hybrid. Check the full job description or apply directly to confirm the work arrangement.
Which team or department does the Backend Engineer - API at xai belong to?
This Backend Engineer - API position is part of the Engineering department at xai. See the full job description for more information about the team structure and responsibilities.
How do I apply for the Backend Engineer - API position at xai?
Click the "Apply Now" button on this page. You will be redirected to xai's official application portal hosted on greenhouse where you can submit your application directly.
When was the Backend Engineer - API job at xai posted?
This Backend Engineer - API position at xai was posted on Apr 24, 2026. Apply as soon as possible — early applications are often reviewed first.
Backend Engineer - API
xai
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