# Founding Product Security Engineer

**Company:** [Arena](https://hotfix.jobs/companies/arena)
**Location:** San Francisco, CA, California
**Role:** Security Engineering
**Salary:** $210k – $320k/yr
**Experience:** 6+ years
**Skills:** Threat Modeling, Authentication, Authorization, Identity Systems, Api Security, Node.js, TypeScript, Python, Go, Distributed Systems, Api Gateway, Rate Limiting, Secure Coding, Incident Response, Security Architecture
**Posted:** 2025-12-18

> Leads product security strategy, designs and implements identity, auth, and secure inference paths for a large-scale AI evaluation platform. Requires 6+ years securing user-facing systems with backend proficiency and threat modeling expertise.

## Job Description

## Responsibilities

- Own the product security vision for Arena, ensuring security and trust are core to every stage of our product lifecycle
- Design and implement the identity, authentication, authorization, and account-lifecycle systems that protect Arena against credential stuffing, account takeover, and API-key compromise
- Secure the model inference path end-to-end — provider credential handling, API gateway, rate limiting, quota enforcement, and protections against secret and prompt exfiltration
- Lead threat modeling and security architecture reviews for new and existing product features
- Collaborate with infrastructure and product engineering to design secure APIs, data flows, and identity systems that scale
- Improve developer velocity by creating secure-by-default frameworks, libraries, and tooling for internal teams
- Apply adversarial thinking to continuously test and evolve platform defenses
- Partner with incident response to quickly assess, contain, and remediate security events, and lead deep postmortems to improve defenses
- Stay ahead of the curve by monitoring emerging attack techniques and applying cutting-edge security research to our platform
- Mentor engineers across the company on secure coding practices, architecture trade-offs, and operational security

## Requirements

- 6+ years of experience in software engineering or security engineering, including staff-level scope in securing large-scale, user-facing platforms
- Strong experience with threat modeling, secure architecture design, and risk assessment
- Hands-on experience building security features into production systems at scale (millions of DAU / billions of requests)
- Deep knowledge of authentication, authorization, and identity systems, including session management and credential-abuse resistance
- Strong knowledge of distributed systems security, API security, and secure data-pipeline design
- Proficiency in backend development (**Node.js**, **TypeScript**, **Python**, or **Go**) and willingness to work across the stack when needed
- Excellent communication skills, able to build alignment across engineering, product, and leadership teams

## Nice-to-Haves

- Experience securing AI/ML inference paths, API gateways, or high-volume public APIs
- Experience building behavioral-signal or fingerprinting platforms used by trust & safety or abuse teams
- Contributions to open-source security tools or research
- Background in securing real-time, interactive platforms at scale
- Experience leading security incident response end-to-end, including blameless postmortems at a company with meaningful external exposure

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