Security Engineer, Application Security
Role Overview
As a Security Engineer focused on Application Security at Mercor, you'll take ownership of application security processes, integrating security into the development lifecycle and managing vulnerability remediation. This senior-level role involves collaborating with a dynamic team of researchers and engineers, driving impactful security initiatives that protect sensitive AI training data and enhance the overall security posture of the platform.
Perks & Benefits
Mercor offers equity ownership in a profitable, high-growth company, along with relocation support to major cities like San Francisco, NYC, or London. The role includes a daily meal stipend, premium fitness membership, and comprehensive health insurance, fostering a culture of well-being and support. Working remotely on designated Fridays provides flexibility, while the collaborative environment emphasizes career growth and ownership of critical security functions.
Full Job Description
About Mercor
Mercor is defining the future of work. We partner with leading AI labs and enterprises to provide the human intelligence essential to AI development.
Our vast talent network trains frontier AI models in the same way teachers teach students: by sharing knowledge, experience, and context that can't be captured in code alone. Today, more than 30,000 experts in our network collectively earn over $2 million a day.
Mercor is creating a new category of work where expertise powers AI advancement. Achieving this requires an ambitious, fast-paced and deeply committed team. You’ll work alongside researchers, operators, and AI companies at the forefront of shaping the systems that are redefining society.
Mercor is a profitable Series C company valued at $10 billion. We work in-person five days a week in our San Francisco, NYC, or London offices.
You'll own application security at a company where the app layer is the highest-priority security surface. This is not a scan-and-triage role. You'll embed in the development lifecycle, review code for exploitable flaws, build security tooling into CI/CD, and drive vulnerability remediation across a platform serving 300K+ experts and enterprise clients processing sensitive AI training data.
We use AI heavily in our own security work. You should be comfortable building alongside AI code-gen tools, using LLMs to accelerate code review and threat modeling, and automating away the repetitive work that slows AppSec programs down. If you'd rather write a CodeQL query than file a Jira ticket, you'll fit in here.
We're in-person five days a week at our SF headquarters, with first Fridays remote.
What You'll Build:
Security review workflows embedded in the SDLC - PR-level analysis that catches auth bugs, injection flaws, and business logic errors before they ship
SAST/DAST pipelines integrated into CI/CD - shifting security left without slowing down deploys
Vulnerability management processes that prioritize by real exploitability, not CVSS score
Secure coding standards and guardrails that make the safe path the easy path for 50+ engineers
Threat models for new features and architecture changes - especially around AI data pipelines, payment flows, and multi-tenant boundaries
Bug bounty program operations - triaging HackerOne reports, validating findings, and driving fixes to closure
What We're Looking For
You've found and fixed real vulnerabilities in production applications - not just run scanners
Deep understanding of web application security: OWASP Top 10 is baseline, you think in terms of attack chains and business logic flaws
Strong in at least one of Python, TypeScript, or Go - you can read a PR and spot the auth bypass
Experience building or tuning SAST/DAST tooling (Semgrep, CodeQL, Snyk, Burp, or similar)
You understand modern web frameworks, APIs, and authentication patterns well enough to threat model them
Experience managing a vulnerability pipeline - from discovery through prioritization to verified remediation
5+ years of professional experience in application security, security engineering, or software engineering with a strong security focus
Bonus Points
Experience running or triaging a bug bounty program (HackerOne, Bugcrowd)
Offensive security skills - you've done penetration testing and can think like an attacker
Experience securing AI/ML applications - model serving APIs, training data pipelines, prompt injection defense
Familiarity with supply chain security - dependency scanning, registry firewalls (Socket, Snyk)
You've built custom security tooling that a team still uses
Contributions to open source security projects or published vulnerability research
Why Mercor
The problem is real. Application security at scale is hard - you'll build defenses that matter across a fast-moving platform.
AI-native AppSec. You'll use frontier AI tools daily - for code review, vulnerability analysis, and anything that benefits from an AI co-pilot.
Ownership from day one. You'll own the entire application security domain - from code review processes to CI/CD security to bug bounty operations.
See the future early. Working alongside AI labs means you'll understand frontier model capabilities months before the market.
Benefits
Equity ownership in a high-growth, profitable company
Relocation support to San Francisco, NYC, or London as needed
Housing support near our SF office
Daily meal stipend
Premium fitness membership at Equinox
Comprehensive health insurance
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