---
title: 'Member of Technical Staff — Reliability-CI Infrastructure at RadixArk'
canonical: 'https://feeny.ai/job/member-of-technical-staff-reliability-ci-infrastructure-radixark-palo-alto-f6br2hsn8yzs'
type: 'job'
last_seen: '2026-09-13'
---

# Member of Technical Staff — Reliability-CI Infrastructure at RadixArk

- **Company:** RadixArk
- **Location:** Palo Alto, CA
- **Posted:** 2026-04-20
- **Last confirmed live:** 2026-09-13
- **Apply:** https://job-boards.greenhouse.io/radixark/jobs/4226122009

## Job description

## About the Role

RadixArk is hiring a Member of Technical Staff — CI / Infrastructure to own the infrastructure that keeps SGLang moving. Our CI system runs 300+ GPU tests across NVIDIA, AMD, Intel, and Ascend hardware pools, gating every commit to one of the fastest-growing open-source LLM inference engines. When CI is green and fast, 100+ contributors ship with confidence. When it isn't, the entire project stalls. That bottleneck is your problem to solve.

You won't just maintain pipelines — you'll architect them. You'll replace brittle static thresholds with regression-based detection, harden runners against supply-chain attacks from fork PRs, and cut cycle times so contributors get feedback in minutes, not hours. You'll work directly with core maintainers, hardware partners, and the open-source community to keep the system that gates every merge request trustworthy, fast, and secure.

This is not a role for someone who wants to write CI YAML and walk away. It's for an engineer who treats CI infrastructure the way we treat serving infrastructure — as a system worth designing well.

## What You’ll Do

- Own CI reliability end-to-end — triage failures, distinguish real regressions from flaky tests and infra issues, keep main green
- Build regression-based CI — replace hardcoded static thresholds with automated baseline comparison (metrics pipeline, durable storage, detection logic)
- Harden runner infrastructure — ephemeral runners, container isolation, security hardening for fork PR execution
- Cut CI time — right-size eval suites, deduplicate server startups, separate PR smoke tests from nightly full runs
- Improve developer experience — faster feedback, clearer failure messages, workflow orchestration

## Requirements

-

- 3+ years operating CI/CD at scale (GitHub Actions, Buildkite, Jenkins, GitLab CI, or similar)
- Deep Linux, Docker, GPU computing knowledge
- Self-hosted runner management experience
- Strong Bash and Python
- Security mindset — CI supply chain risks, fork PR attack vectors, runner hardening
- NVIDIA GPU drivers, CUDA, NCCL, InfiniBand/RDMA experience in CI contexts
- Familiarity with ML inference workloads (model loading, KV cache, quantization)

## Nice to Have

- Large open-source project CI experience (100+ contributors)
- AMD ROCm or Intel XPU CI pipelines

What Success Looks Like

- Day 20 — Full CI landscape understood, daily triage taken over, top recurring flaky tests fixed, PR CI time reduced 30%+
- Day 40 — Regression-based checks live on nightly CI, ephemeral runner prototype deployed, runner isolation in place
- Day 60 — Zero flaky tests. Main CI 100% green when no real regression exists

How to Apply

Reach out via Slack or email. CI fix PRs to major open-source projects are worth more than a resume.

## About RadixArk

RadixArk is an infrastructure-first company built by engineers who've shipped production AI systems, created SGLang (30K+ GitHub stars, the fastest open LLM serving engine), and developed Miles (our large-scale RL framework). Founded by AI infrastructure veterans from xAI and NVIDIA, we're on a mission to democratize frontier-level AI infrastructure by building world-class open systems for inference and training. Our team has optimized kernels serving billions of tokens daily, designed distributed training systems coordinating 10,000+ GPUs, and contributed to infrastructure that powers leading AI companies and research labs.

## Compensation

Depending on background, skills, and experience, the expected annual salary range for this position is $200,000 - $400,000 USD + equity.

## Equal Opportunity

RadixArk is an Equal Opportunity Employer and is proud to offer equal employment opportunity to everyone regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, gender identity, veteran status, and more.

## About RadixArk

## Company Overview
- **One-liner**: RadixArk builds open, large-scale inference and training systems to democratize access to frontier AI infrastructure for the entire AI community.
- **Entity Type**: Private (Seed stage)
- **Headquarters**: San Francisco, California, United States
- **Founded**: 2025
- **Founders**: Ying Sheng (CEO) and Banghua Zhu

## Core Business
- **Primary industry/industries**: AI Infrastructure, Deep-Tech, Open Source Software
- **Target customers**: Individual developers, startups, enterprises, and research labs building and deploying AI systems at scale.
- **Mission or purpose statement**: "Make frontier-level AI infrastructure open and accessible to everyone." [radixark.com](https://radixark.com/)

## Products & Services
- **[SGLang (Inference Engine)](https://radixark.com/)**: An open-source, high-performance serving engine for AI models. It has become a de facto standard, powering trillions of tokens daily for leaders like Google, Microsoft, NVIDIA, and xAI. RadixArk is the primary steward. **Type:** Open-Source Software / Managed Service
- **[Miles (RL Framework)](https://radixark.com/blog/radixark-launches-100m-seed)**: An open-source framework for large-scale reinforcement learning and post-training. Designed for efficiency and stability, it has been adopted for large-scale MoE training. **Type:** Open-Source Software
- **Managed Infrastructure & Tooling**: Built on top of SGLang and Miles, RadixArk offers managed services for the full lifecycle of AI development, from training to inference, for teams developing AI at scale. **Type:** Managed Service / Platform

## Market Standing
- **Valuation/Market Cap**: $400 million post-money valuation (as of May 2026) [cbinsights.com](https://www.cbinsights.com/company/radixark)
- **Key Metric**: $100 million total funding (Seed Round)
- **Notable Investors/Partners**: Accel (lead), Spark Capital (co-lead), NVentures (NVIDIA's venture arm), and participation from Google, Microsoft, and other strategic partners. [radixark.com](https://www.radixark.com/blog/radixark-launches-100m-seed)
- **Growth Signals**: The company has 19 employees as of mid-2026 but has seen a monthly headcount growth of +55.6%. Its open-source projects (SGLang and Miles) are already adopted by industry giants and research labs, indicating massive traction and developer mindshare. [linkedin.com](https://www.linkedin.com/company/radixark)

## Competitive Advantages
- **Open-Source Moat**: Its core products, SGLang and Miles, are open-source community standards with deep adoption. This creates a network effect and developer loyalty that is hard for proprietary competitors to replicate.
- **First-Principles Engineering Culture**: The company treats infrastructure engineering as a core creative discipline, not a support function, leading to deeper system-level innovations.
- **Top-Tier Talent & Backing**: Founded by the creators of SGLang and backed by Accel, Spark Capital, and NVIDIA, giving it immediate credibility, capital, and access to frontier hardware.
- **Clear Mission**: Focusing on making infrastructure "10x cheaper and 10x more accessible" directly addresses a massive pain point for the entire AI ecosystem. [radixark.com](https://www.radixark.com/)

## Strategic Focus
- **Growing SGLang & Miles**: Using the $100M seed to accelerate support for new model architectures, hardware platforms, and community improvements.
- **Building Managed Services**: Developing the managed infrastructure and tooling layer on top of its open-source cores to serve a wider range of customers.
- **Hiring Deeply Technical Talent**: Actively recruiting top-tier engineers for kernels, compilers, training systems, and TPU systems to maintain its engineering edge.
- **Expanding Global Reach**: With a Sales role based in Singapore, the company is signaling an intention to serve the APAC market.

## Why Work Here
- **Impactful Mission**: Employees contribute directly to making frontier AI infrastructure a shared foundation, working on problems that affect the entire AI ecosystem.
- **Engineering-Centric Culture**: The company explicitly states that "infrastructure engineering is not a support function," making it an ideal environment for deep-tech systems engineers who want to solve hard, first-principles problems. [radixark.com](https://www.radixark.com/blog/radixark-launches-100m-seed)
- **Work with Open Source at Scale**: You will be contributing to and stewarding widely-used open-source projects (SGLang, Miles) that power trillions of tokens daily.
- **Strong Backing & Early Stage**: Joining a well-funded seed-stage company with a $400M valuation offers significant upside and the chance to shape the company's culture and direction from an early stage.
- **Location & Hybrid Policy**: The company is headquartered in Palo Alto and San Francisco, California, with most roles listed as in-office. They also have a role in Singapore.
- **Notable Perks**: The company's blog emphasizes a culture of being "focused, humble, fearless, and meticulous," which appeals to mission-driven engineers.

## Sources
1. [RadixArk Official Website](https://radixark.com/)
2. [RadixArk Blog: $100M Seed Announcement](https://www.radixark.com/blog/radixark-launches-100m-seed)
3. [RadixArk Jobs on Greenhouse](https://job-boards.greenhouse.io/radixark)
4. [RadixArk LinkedIn Page](https://www.linkedin.com/company/radixark)
5. [CBInsights Company Profile](https://www.cbinsights.com/company/radixark)

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