Application Security Engineer

About Opendoor

At Opendoor our mission is to tilt the world in favor of homeowners and those who aim to become one. Homeownership matters. It's how people build wealth stability and community. It's how families put down roots how neighborhoods strengthen how the future gets built. We're building the modern system of homeownership giving people the freedom to buy and sell on their own terms. We’ve built an end-to-end online experience that has already helped thousands of people and we’re just getting started.

About The Role

Our Security Engineering team builds intelligent systems that protect Opendoor and our customers while enabling unprecedented engineering velocity. We apply software engineering and AI to solve security problems across product infrastructure and operations by building guardrails where they matter not gates where they don't.

As our Application Security Engineer you'll own how we find prioritize and drive down application-layer risk across the consumer flows that put cash offers in homeowners’ hands the GraphQL APIs that power our products and the AI agents and vibe-coded tools our engineers ship every week. The job is to make it safe to build fast not to slow things down.

What You'll Do

● Define build and operate Opendoor’s application vulnerability identification capability - the tooling triage workflow and remediation techniques across our consumer products internal admin tools and GraphQL API powering home acquisition resale mortgage title and escrow. 

● Assess rationalize and own our AppSec tooling stack - static and dynamic security testing software supply chain risk detection and secrets scanning and integrate findings into developer workflows where engineers already live (GitHub Linear Slack).

● Own and mature our HackerOne program: tightening the triage workflow improving signal to noise on incoming reports strengthening researcher relationships and closing the loop with engineering teams so root causes get addressed quickly. 

● Lead threat modeling and security design reviews for new services APIs and mobile features. Turn the patterns you see into rules lint checks and CI guardrails so the next team doesn't make the same mistake.

● Build AI agents and automated workflows that triage vulnerability reports validate exploit reproductions and draft remediation pull requests replacing manual security review with high-signal automation.

● Partner with engineering teams to harden authentication authorization and input validation across our codebase and production services including the GraphQL gateway (Apollo) and our Kubernetes workloads - while driving a shift-left strategy that catches vulnerabilities before they ship.

● Build Opendoor’s offensive security capability. Scope and run internal security testing red team exercises and adversarial analysis of our highest-risk flows ensuring findings directly harden detection and response.  

● Set the bar for what "secure by default" looks like for AI-maximalist engineering including vibe-coded apps MCP servers and agent-driven workflows that touch production data.

● Build Opendoor’s security culture by establishing secure design standards embedding into engineering team rituals and developing a strong security mindset - creating a foundation for engineers to think like attackers without slowing down. 

Tech Stack

● Languages: Go Python TypeScript Ruby Terraform

● Cloud: AWS GCP Azure Kubernetes Apollo GraphQL

● AppSec Tooling: GitHub Advanced Security (CodeQL Dependabot secret scanning) Semgrep HackerOne Burp Suite Cloudflare WAF

● AI Tooling: Claude OpenAI various agent frameworks MCP — used heavily for vulnerability triage exploit verification and remediation drafting

What You'll Need

● Deep conviction that AI and automation should eliminate manual work and increase the team's impact and a track record to prove it. You’ve built agentic systems that replaced reactive security work not just configured off-the-shelf tools.

● Comfort operating with high autonomy in ambiguous environments. You’ve defined what “good” looks like in a domain where no playbook existed you’re energized by that not unsettled by it. 

● Business enablement security mindset. You measure success by business impact and informed risk-taking not by tickets opened or pen test reports filed.

● 5+ years of application security or software engineering experience with a security focus with strong skills in at least one of Python Go TypeScript or Ruby and the ability to read and write code across the others.

● Hands-on expertise across the security risk detection toolchain with real deployment experience using GitHub Advanced Security Semgrep or equivalent.

● Strong grasp of common application and API vulnerability classes including GraphQL REST and gRPC security pitfalls - broken authorization mass assignment introspection exposure insecure direct object references.

● Practical threat modeling skills. You can take an architecture diagram and a 30-minute conversation and walk out with the three things that actually matter.

● Experience with cloud and container security on AWS and Kubernetes including identity and access management secrets management and continuous integration / continuous deployment pipeline security.

● Humility and genuine curiosity. You're as excited to learn from product engineers and enable their work as you are to break things.

Bonus Points

● Offensive security experience including pentesting API security or mobile security and/or red team operations.

● Experience running a bug bounty or coordinated disclosure program at scale.

● Mobile application security review experience (iOS and Android).

● Experience securing AI and machine learning pipelines agent frameworks or MCP-style integrations.

● OSCP OSWE or similar offensive certifications.

Location

This role is based in our downtown Miami office in-person four days per week (Monday Tuesday Thursday Friday). Candidates must be based within commuting distance of the office.

What We Do

Founded in 2014 Opendoor’s mission is to empower everyone with the freedom to move. We believe the traditional real estate process is broken and confusing. It often comes with unexpected costs the added burden of coordinating multiple third parties and the uncertainty of a transaction falling through. Our goal is simple: build a digital end-to-end customer experience that makes buying and selling a home simple certain and fast. We have assembled a dedicated team with diverse backgrounds and talents across engineering operations design operations mortgage finance legal and more to deliver strong results. More than 85000 customers have selected us as a trusted partner in handling one of their largest financial transactions.

Why Work With Us

We’re on a mission to power life’s progress one move at a time

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