Backend Engineer - API

Xai; Greater London; On-site; GBP 107,000 - 262,000; Full time

Benefits offered by this job

Equity

Healthcare coverage

Dental coverage

Cash plan

Income protection

Life insurance

Discounts and perks

Job summary

SpaceXAI, a frontier AI company, is hiring a backend engineer to scale production infrastructure for model serving. You will be hands-on and collaborate across teams to deliver reliable systems in a fast-paced environment.

The role emphasizes Rust or C++ expertise, designing distributed services, and operating databases at scale, with a strong focus on observability, reliability, and performance. Equity and comprehensive benefits are part of the total rewards.

Qualifications

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

Responsibilities

• Build the SpaceXAI API that serves our models to developers worldwide.
• Own the end-to-end system responsible for high-throughput inference with low latency and high availability.

Skills

Rust

C++

Distributed systems

Observability

Tools

PostgreSQL

Clickhouse

MongoDB

Job description

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.