Senior Application Security Engineer

Location:

- Remote - United States

THE ROLE

Sardine makes risk and payment decisions for banks and fintechs. Our customers audit us closely, and application security is a large part of what they examine.

Money moves through this platform, so real adversaries study it. Your job is to find what they would find, especially authorization flaws and business logic abuse, and then make the whole class of bug go away.

The application security team is small. The estate is large: Go, Node.js, Python, Ruby, and Java services running on multi-cloud and Kubernetes. That ratio shapes the work. Findings arrive from scanners, code review, testing, threat modeling, pentesters, and bug bounty hunters. You turn that stream into a pipeline that validates, routes, and closes issues with as little manual effort as possible. Then you use what the pipeline tells you to remove root causes: secure defaults, patterns engineers reach for first, and fixes that hold.

Little here is pre-decided. You determine where the risk is and go after it.

THE WORK

WHERE MOST OF YOUR TIME GOES

RUNNING AND AUTOMATING THE VULNERABILITY PIPELINE

- Triage, validate, route, and drive remediation of findings from every source: SAST, DAST, SCA, code review, pentests, and bug bounty

- Build the automation that removes manual effort from each of those steps

- External pentests and bug bounty program: set scope, direct the testers, judge severity, and close the loop

MAKING BUG CLASSES GO AWAY

- Spot the patterns across findings and remove the root cause, not just the instance

- Set the secure patterns and defaults that make the right way the easy way

- Write custom static analysis rules for our own anti-patterns, so a fixed bug class stays fixed

- Review platform-layer controls (authorization, service identity, secrets handling, gateway enforcement), find the gaps, and push the owning teams until they are closed

- Work alongside engineers on fixes that are simple, get adopted, and hold

ALSO PART OF THE JOB

- Hands-on testing of our applications and APIs, and manual code review of high-exposure services, with depth in authorization and business logic

- Threat modeling on new and high-exposure designs

- Security enablement across engineering, including a security champions program

WHAT WE'RE LOOKING FOR

- Vulnerability management, automated. Experience running vulnerability management end to end, and automating it with code against scanner, ticketing, and source-control APIs

- An engineering background. You have shipped and maintained real software. You read unfamiliar code quickly, review it rigorously, and reason about architecture and failure modes.

- Ownership to done. You take problems all the way through, including fixes that depend on other teams. You follow up on the fix you recommended three sprints ago.

- Judgment over tenure. We care more about the depth of your judgment than your years of experience.

- Code auditing in at least one of Go, Python, Node.js, Ruby, or Java, and the willingness to work in the rest

- Practical command of the OWASP Top 10, with real depth in broken access control and business logic flaws

- SAST, DAST, and SCA in CI/CD, tuned so engineers trust the output. Cloud fundamentals on GCP or AWS. Docker and Kubernetes.

- You separate real findings from theoretical ones.

- You disagree in the open, with evidence, and update when someone brings better evidence.

- Your influence travels asynchronously, across time zones, to people with strong opinions and no reporting line to you.

BONUS

- Scaling security tooling across many repositories, languages, and build systems

- Prior experience writing custom static analysis rules (Semgrep, CodeQL, or similar)

- Fintech, payments, or other environments under serious third-party security review (PCI DSS, SOC 2, customer audits)

- Fully distributed, asynchronous engineering experience

- Offensive experience in whatever form you found it. Pentesting on web, API, mobile, or cloud is the most directly relevant. Hardware and embedded work, physical security and lock sport, red team engagements, protocol and radio work, and CTF or bug bounty results all count.

- Advanced offensive certifications. OSWE and BSCP are the most relevant; CPTS, CRTO, and similar also count.

- Public work: research, tooling, disclosures, talks