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# Application Security Engineer

- **Company:** Hark's Co.
- **Location:** San Jose, CA, United States
- **Experience:** Experienced
- **Contract:** Permanent contract
- **Skills:** Application Programming Interfaces (APIs), Artificial Intelligence, User Authentication, Cloud Computing, Code Review, Mobile Application Software, Python (Programming Language), OAuth, Open Source Technology, OpenID, Open Web Application Security, Secure Coding, Session Management, Security Information and Event Management, Software Engineering, TypeScript, Datadog, Large Language Models, Software Security, Swift (Programming Language), Backend, Kotlin, Stripe, Production Code, Roblox, Prompt Injection, Discord, Static Application Security Testing
- **Published:** November 7, 2026
- **Apply:** https://www.juju.com/job/28_25303_f319374f5f9d9e78d75a045969876896

## About the Role

* 4-8 years of hands-on application or product security engineering experience.
 * Strong software engineering skills; you can read, write, and ship production code (Go strongly preferred; Python, TypeScript, Swift, or Kotlin also valuable).
 * Deep understanding of web and API vulnerability classes (OWASP Top 10, SSRF, IDOR/BOLA, authz flaws, injection) and how to fix them at the root.
 * Hands-on experience with OAuth 2.0 / OIDC, session management, and securing multi-tenant systems.
 * Experience running secure code review and threat modeling in a fast-moving engineering org.
 * Experience turning scanner and runtime findings into fixes using tools like Wiz Code, Wiz Cloud, and Datadog SIEM (or equivalent SAST/SCA, CNAPP, and SIEM tools).
 * Real curiosity about LLM and agent security; this is new territory and we want someone excited to figure it out., * Experience at a security-forward product company (Stripe, Coinbase, Discord, Roblox, Netflix) or an offensive security consultancy (Trail of Bits, Bishop Fox, NCC Group).
 * Mobile application security experience (iOS/Android).
 * Prior work on LLM/agent threat modeling, prompt injection defenses, or AI red teaming.
 * Bug bounty, CVE, or open source security contributions.

## Description

We're hiring a Member of Technical Staff (Application Security Engineer) to own the security of the software Hark ships. You'll review design and code, find and fix vulnerabilities in our backend services, mobile apps, and third-party integrations, and build the guardrails that let engineers move fast without shipping bugs. Our agents act on behalf of users across their apps and data, so you'll also be defining how to secure LLM and agent systems, a space with very few established playbooks., * Threat-model new features and services, with a focus on agent/LLM attack surfaces (prompt injection, tool misuse, data exfiltration, cross-tenant access).

 * Review code and designs for Hark's backend services (primarily Go), APIs, and mobile apps; fix vulnerabilities directly when it's faster than filing a ticket.
 * Secure authentication, authorization, and session handling across our consumer product, including OAuth integrations with third-party platforms.
 * Build and tune SAST, dependency, and secrets scanning in CI so findings are high-signal and developers actually act on them.
 * Triage and remediate findings from pentests and our vulnerability disclosure program.
 * Partner with engineering to embed security into the development lifecycle through paved roads, secure defaults, and reusable libraries.