Security Engineer (For independent contractors)

Help build and improve how Booking identifies and manages automated traffic across its web and mobile products. You’ll engineer detection and classification capabilities that distinguish AI-driven bots, other automation, legitimate bots, people, and unknown traffic—and help teams take proportionate action without disrupting genuine customers. What you’ll do: Build, test, and tune bot-detection signals and classification logic across web, mobile, APIs, and edge services.

Improve the telemetry used to understand bot activity, working with application and platform teams to close gaps in coverage, data quality, and attribution. Maintain detection logic and configuration as production software: version changes, validate them against representative traffic, and use staged rollouts and rollback controls. Measure detection coverage and quality, including precision, recall, unknown traffic, and false positives affecting customers and legitimate automated services.

Analyze changes in bot behaviour, traffic patterns, and evasion techniques; turn findings into improved signals and detection tests. Build monitoring and reporting that surfaces coverage gaps, material traffic changes, and detection quality for technical and business teams. Work with product and service teams to translate detection results into proportionate decisions such as allow, monitor, challenge, restrict, or block. Validate changes against business outcomes and customer impact, and continuously improve the detection capability based on results.

What you’ll bring: Experience building or operating production software, security systems, or traffic-protection capabilities. Strong coding skills in a language such as Python, Go, or Java, with experience testing and maintaining production systems. Experience analyzing event or traffic data and developing detection logic, behavioral signals, or classification systems. Understanding of web, mobile, API, or edge security and common automated-traffic and abuse patterns.

Ability to measure detection quality and balance security effectiveness against false positives and customer impact. Clear communication skills and the ability to work across security, engineering, data, and product teams.

Helpful experience: Bot management, web application firewalls, content delivery networks, or edge security controls. Mobile app security signals, client-side challenges, or integration of security SDKs. Statistical or machine-learning methods for classification, anomaly detection, or behavioral analytics. Experiment design, traffic analysis, dashboards, or security reporting. Abuse prevention, fraud detection, threat research, or incident response.