Backend Engineer - API — Opportunihub
Job

Backend Engineer - API

Xai · London

At a glance

Type
Job
Organisation
Xai
Location
London
Work mode
On-site
Deadline
Rolling / not stated
Posted
5 Aug 2026

About this job

&lt;div class=&quot;content-intro&quot;&gt;&lt;p&gt;&lt;span style=&quot;font-family: arial, helvetica, sans-serif;&quot;&gt;SpaceXAI’s mission is to create AI systems that can accurately understand the universe and aid humanity in its pursuit of knowledge.&amp;nbsp;&lt;/span&gt;&lt;span style=&quot;font-family: arial, helvetica, sans-serif;&quot;&gt;Our team is small, highly motivated, and focused on engineering excellence. This organization is for individuals who appreciate challenging themselves and thrive on curiosity. &lt;/span&gt;&lt;span style=&quot;font-family: arial, helvetica, sans-serif;&quot;&gt;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. &lt;/span&gt;&lt;span style=&quot;font-family: arial, helvetica, sans-serif;&quot;&gt;All employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates.&lt;/span&gt;&lt;/p&gt;&lt;/div&gt;&lt;h3 data-pm-slice=&quot;1 1 []&quot;&gt;&lt;span style=&quot;font-family: arial, helvetica, sans-serif;&quot;&gt;ABOUT THE ROLE:&lt;/span&gt;&lt;/h3&gt; &lt;p&gt;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.&lt;/p&gt; &lt;h3&gt;&lt;span style=&quot;font-family: arial, helvetica, sans-serif;&quot;&gt;RESPONSIBILITIES:&lt;/span&gt;&lt;/h3&gt; &lt;ul&gt; &lt;li&gt;Build the SpaceXAI API that serves our models to developers worldwide&lt;/li&gt; &lt;li&gt;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&lt;/li&gt; &lt;/ul&gt; &lt;h3&gt;&lt;span style=&quot;font-family: arial, helvetica, sans-serif;&quot;&gt;BASIC QUALIFICATIONS:&lt;/span&gt;&lt;/h3&gt; &lt;ul&gt; &lt;li&gt;Expert knowledge of either Rust or C++&lt;/li&gt; &lt;li&gt;Experience in designing, implementing, and maintaining reliable and horizontally scalable distributed systems&lt;/li&gt; &lt;li&gt;Knowledge of service observability and reliability best practices&lt;/li&gt; &lt;li&gt;Experience in operating commonly used databases such as PostgreSQL, Clickhouse, and MongoDB&lt;/li&gt; &lt;/ul&gt; &lt;h3&gt;&lt;span style=&quot;font-family: arial, helvetica, sans-serif;&quot;&gt;PREFERRED SKILLS AND EXPERIENCE:&lt;/span&gt;&lt;/h3&gt; &lt;ul&gt; &lt;li&gt;Experience with LLM inference engines and serving frameworks (e.g., SGLang, TensorRT, vLLM)&lt;/li&gt; &lt;li&gt;Experience designing or building with agent SDKs and agent orchestration frameworks&lt;/li&gt; &lt;li&gt;Experience with Docker, Kubernetes, and containerized applications&lt;/li&gt; &lt;li&gt;Expert knowledge of gRPC (unary, response streaming, bi-directional streaming, REST mapping)&lt;/li&gt; &lt;/ul&gt; &lt;h3&gt;&lt;strong&gt;COMPENSATION AND BENEFITS:&lt;/strong&gt;&lt;/h3&gt; &lt;p&gt;£107,000 - £262,000 GBP&lt;/p&gt; &lt;p class=&quot;p1&quot;&gt;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.&lt;/p&gt;&lt;div class=&quot;content-conclusion&quot;&gt;&lt;p&gt;&lt;em&gt;SpaceXAI is an equal opportunity employer. For details on data processing, view our &lt;/em&gt;&lt;em&gt;&lt;a href=&quot;https://x.ai/legal/recruitment-privacy-notice&quot; target=&quot;_blank&quot;&gt;Recruitment Privacy Notice&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&lt;/div&gt;<p>Find <a href="https://www.arbeitnow.co.uk">Jobs in United Kingdom</a> on Arbeitnow</a>

How to apply

  1. 1 Read the full details above and confirm you meet the eligibility criteria.
  2. 2 Prepare your documents — an updated CV, and any cover letter, proposal or certificates required.
  3. 3 Click Apply on official site to complete your application on Xai’s official page.
  4. 4 Submit as early as possible — many close once filled.
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Frequently asked questions

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Review the full details and eligibility on this page, prepare your documents, then use the “Apply on official site” button to complete your application on Xai’s official page.

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