---
title: 'Member of Technical Staff — Backend/API Platform at RadixArk'
canonical: 'https://feeny.ai/job/member-of-technical-staff-backend-api-platform-radixark-palo-alto-yfm7dtenvy0k'
type: 'job'
last_seen: '2026-09-13'
---

# Member of Technical Staff — Backend/API Platform at RadixArk

- **Company:** RadixArk
- **Location:** Palo Alto, CA
- **Posted:** 2025-12-30
- **Last confirmed live:** 2026-09-13
- **Apply:** https://job-boards.greenhouse.io/radixark/jobs/4087910009

## Job description

## About the Role

RadixArk is looking for a Member of Technical Staff — Backend/API Platform Engineer to build the API layer, control plane, and platform services that power SGLang and Miles in production. You'll design and implement the REST/gRPC APIs, authentication systems, multi-tenancy isolation, and monitoring infrastructure that thousands of developers and companies rely on. This role bridges high-performance inference/training systems with production-grade platform engineering.

## Requirements

- 4+ years experience building production backend systems, APIs, or platform infrastructure

- Bachelor's or Master's degree in Computer Science, Engineering, or equivalent industry experience

- Strong proficiency in Python, Go, or Rust with production-quality code standards

- Experience designing and building REST/gRPC APIs at scale

- Solid understanding of distributed systems, databases, caching, and message queues

- Experience with authentication, authorization, rate limiting, and multi-tenancy

- Familiarity with cloud platforms (AWS, GCP, Azure) and Kubernetes

- Experience with monitoring and observability tools (Prometheus, Grafana, DataDog)

- Understanding of ML serving infrastructure or high-throughput systems is a plus

## Responsibilities

- Design and build production APIs for SGLang and Miles: REST/gRPC endpoints, client SDKs, API versioning

- Implement authentication, authorization, and rate limiting systems for multi-tenant deployments

- Build control plane infrastructure: job scheduling, resource allocation, model deployment management

- Create monitoring, logging, and observability systems for production inference and training workloads

- Design and implement billing integration, usage tracking, and quota management

- Build management dashboards and admin tools for cluster operations

- Ensure API reliability, performance, and security at scale

- Implement multi-tenancy isolation and security boundaries

- Create deployment automation, CI/CD pipelines, and rollback procedures

- Write comprehensive API documentation and integration guides

- Partner with Systems Engineers to optimize end-to-end latency from API → serving layer

- Debug production issues and implement reliability improvements

## 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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