Technical Fraud Specialist

Kleinanzeigen; Madrid; Hybrid; EUR 60,000 - 90,000; Full time

Benefits offered by this job

Private health insurance

Gym Pass

Remote working allowance

Personal development budget

Referral program

Competitive pay

Job summary

Kleinanzeigen, Germany's leading online classifieds, seeks a technical fraud analyst to join our growing fraud team. You’ll work at the intersection of data, product, engineering, and CS to identify fraudulent behaviour, monitor for credential stuffing attacks, and build proactive rule-based defenses.

This hybrid role is based in Barcelona, Spain. You’ll influence the roadmap and collaborate with engineers, product, and CS to keep Kleinanzeigen safe while advancing detection capabilities.

Qualifications

• 4+ years of fraud analytics, trust & safety, or a similar technical role in a C2C marketplace or traditional e‑commerce environment.

Responsibilities

• Analyze fraud patterns using marketplace and behavioral data to uncover new attack vectors, emerging threats, and operational gaps.

Skills

Fraud analytics

SQL

Tableau

Python

Rule engines

Cross-functional communication

Behavioral biometrics

Authentication

Tools

Threatmetrix

Arkose

Sift

Internal-rule system

Job description

Job Description

Kleinanzeigen reaches 36M+ monthly users and is Germany’s leading online classifieds market. We are a sustainability-focused platform where you won't just write code; you will power the services that bridge our high-traffic backend with seamless user experiences.

We are looking for a technical fraud analyst to join our growing fraud team. You’ll work at the intersection of data, product, engineering, and CS. Using your analytical and technical skills, you will identify fraudulent behaviour, monitor for credential stuffing attacks, bot attacks, build pro‑active rule based defenses, and influence the roadmap to keep Kleinanzeigen safe marketplace.

This is a hybrid role, based in Barcelona Spain.

Job requirements

Who You Are

• 4+ years of experience in fraud analytics, trust & safety, or a similar technical role in a C2C marketplace or traditional e‑commerce environment.
• Strong proficiency in SQL and experience with data analysis tools (Tableau, Python, etc.).
• Familiarity with bot detection, account takeovers, credential stuffing, and other common C2C fraud patterns.
• Experience writing technical rules with rule engines (Threatmetrix, Arkose, Sift, internal-rule based system, etc.)
• Excellent cross-functional communication skills - you can translate technical findings for non-technical audience / stakeholders & vice versa.
• A curious, proactive mindset and a passion for solving complex problems that have real‑world impact.
• Profecient with Python for more advanced data analysis & automation
• Experience to authentication, behavioural biometrics, and fraud stemming from user generated content such as ads and messages

Job responsibilities

What You’ll Do

• Analyze fraud patterns using marketplace and behavioral data to uncover new attack vectors, emerging threats, and operational gaps.
• Monitor and respond to credential stuffing attacks, leveraging signals from login, IPs, device fingerprinting, and rate limiting systems.
• Design and implement technical fraud rules, filters, and tools in collaboration with engineering to align fraud prevention efforts and resolve complex incidents.
• Contribute to the strategic fraud prevention roadmap by identifying opportunities for improvements and automation.
• Support incident response and post‑mortems for major fraud events, ensuring learnings feed into product and policy improvements.
• Stay current on industry fraud trends, and tools, bringing external insights to help us stay ahead of attacks.

Job benefits

At Kleinanzeigen, we care about our people — their wellbeing, growth, and life beyond work. Our benefits are designed to support you holistically, giving you flexibility and opportunities to thrive.

Flexibility

• 26 business days of paid annual holidays
• 20 days “work from anywhere”
• Flexible working time (hybrid)
• Paid additional parental leave for both parents
• Extra paid days off for special occasions (e.g. your wedding or a move)

Wellbeing & Support

• Private health insurance
• Gym Pass (may cover up to 70% of gym membership fees)
• 40€ per month as a remote working allowance.

Growth & Development

• Personal development budget
• Learning opportunities to grow your skills and career
• A unique position in an international and dynamic environment
• A flat, collaborative culture where your feedback actively shapes our processes

Perks & Everyday Benefits

• Competitive compensation package (Base salary + annual bonus)
• Flexible Remuneration Program (tax‑efficient options for transport, restaurant vouchers and childcare)
• Corporate benefits and exclusive discounts
• An attractive referral program

Kleinanzeigen is an equal opportunity employer that values diversity and inclusion. We welcome people of all backgrounds, races, religions, colours, national origins, gender identities, sexual orientation, ages, marital status, or disability status.

If this role sparks your interest but you’re not sure you meet every single requirement, we’d still love to hear from you anyway!