xAI

xAI

Posted via Greenhouse

Backend Engineer - API

Posted Aug 5, 2026

Role at a glance

Salary
Not Disclosed
Location
United Kingdom - England - London
Work arrangement
On-site
Employment
Full-time
Experience
Experience in designing, implementing, and maintaining reliable and horizontally scalable distributed systems

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Role Summary

AI-generated

The role focuses on building SpaceXAI’s API for serving models to developers worldwide. It owns the end-to-end infrastructure for high-throughput, low-latency, and highly available inference.

What You'll Do

  • Build the SpaceXAI API that serves models to developers worldwide
  • Own model serving infrastructure for high-throughput inference
  • Implement request routing and SDK development
  • Manage rate limiting and observability
  • Support efficient scaling and high availability

Generated from the employer's posting. Verify important details before applying.

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Qualifications

Expert knowledge of either Rust or C++; experience designing, implementing, and maintaining reliable and horizontally scalable distributed systems; knowledge of service observability and reliability best practices; experience operating PostgreSQL, Clickhouse, and MongoDB.

Required

  • 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

  • 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)

Original job description

Content provided by the employer

SpaceXAI’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 SpaceXAI 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 SpaceXAI, which also includes equity, comprehensive healthcare and dental coverage, cash plan, income protection, life insurance, and various other discounts and perks.

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

xAI

About the company

xAI

Large Enterprise

xAI is a cutting-edge technology company focused on developing advanced artificial intelligence solutions to enhance human capabilities and optimize decision-making processes. Founded by a team of leading experts in AI and machine learning, xAI aims to address complex challenges across various industries, including healthcare, finance, and transportation. By prioritizing ethical AI development, the company is committed to creating innovative tools that empower organizations to harness the full potential of artificial intelligence while ensuring transparency and accountability.