Senior Data Scientist - Fraud Prevention

The Fraud Prevention organization at Nextdoor is dedicated to protecting neighbors from harmful content, fraud, and abuse, and ensuring that neighbors can safely build and participate in local communities on our platform. The team - which consists of Product, Engineering, Design, and Neighborhood Operations (NOPS) - helps develop policies, build detection systems, and deliver moderation tools at scale to keep our platform safe., * Analyze large, complex datasets to identify abuse patterns, fraud signals, and harmful behavior trends.

• Conduct root cause analysis to diagnose safety incidents and emerging risks.
• Evaluate new tool effectiveness (including AI), and impact on agent efficiency and user satisfaction.
• Define and track core metrics (e.g., harm prevalence, violation rates, detection accuracy).
• Navigate the tradeoff between operational efficiency, safety, and user growth/experience.
• Build dashboards and reporting frameworks to track platform health and safety performance.

_Develop Models & Rules

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• Develop heuristics, statistical models, and machine learning solutions for proactive detection of abuse, fraud, or harmful content
• Build prediction systems (e.g., anomaly detection, risk scoring, behavioral profiling).
• Improve automated enforcement and moderation workflows.
• Evaluate model performance and iterate on detection strategies.

_Evaluate Product / Policy Changes Via Experimentation

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• Design and analyze experiments (A/B tests, causal inference) to measure safety feature impact (e.g., login & verification, AI moderation support). Clearly communicate findings to technical and non-technical stakeholders.
• Quantify tradeoffs between operational efficiency, safety, and user growth/experience. Guide TnS team on key tradeoffs in decision-making

_Own Cross-Functional Partnership

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• Partner with Product, Engineering, Operations, Policy, and Legal teams to define safety strategy.
• Influence decision-making through data storytelling and insights.
• Standardize analytical methodologies and tools for scalable decision-making.

• Bachelor's or Master's degree in Statistics, Computer Science, Mathematics, Economics, or a related quantitative field.
• 5+ years of Data Science experience working with large-scale data and statistical analysis, including 1+ year of data science experience in fraud prevention, moderation, or risk.
• Strong analytical and problem-solving skills, with a track record to lead projects from concept to impact.
• Proficiency in SQL and at least one scripting language (e.g., Python or R).
• Expertise in experimentation and causal inference (A/B testing, cohort analysis, pre/post analysis) to evaluate product or policy changes in production environments.
• Hands-on experience with standard Machine Learning and statistical methods (e.g., prediction, classification, anomaly detection, time series), ideally in risk or fraud prevention contexts.
• Ability to collaborate cross-functionally with Product, Engineering, Operations, and Legal/Policy partners; comfortable influencing without direct authority.
• Strong communication, with the ability to translate technical concepts to non-technical stakeholders, including operations leaders and executives.

Nice to Have

• 2+ years of experience in fraud prevention, moderation, or risk in a social platform context.
• Strong experience with anomaly detection and building/deploying machine learning models.
• Experience working with text, image, or behavioral data.

At Nextdoor, we offer a warm and inclusive work environment that embraces a hybrid employment experience, providing a flexible experience for our valued employees.The hiring team will go over these expectations with you if you are being considered for a role near one of our offices in San Francisco, Los Angeles, Chicago, Dallas, New York, and London., Compensation, benefits, perks, and recognition programs at Nextdoor come together to create one overall rewards package. The starting base salary for this role for the San Francisco, CA area is expected to range from $175,000 to $234,000 on an annualized basis, or potentially greater in the event that your 'level' of proficiency exceeds the level expected for the role. The salary range will be determined by the candidate's geographic location. We also expect to award a meaningful equity grant for this role. With quarterly vesting, your first vest date would be within the first 3 months of your start date. Overall, total compensation will vary depending on your relevant skills, experience, and qualifications. We have you covered! Nextdoor employees can choose between a variety of great health plans. At Nextdoor, we empower our employees to build stronger local communities. To create a platform where all feel welcome, we want our workforce to reflect the diversity of the neighbors we serve. We encourage everyone interested in our mission to apply. We do not discriminate on the basis of race, gender, religion, sexual orientation, age, or any other trait that unfairly targets a group of people. In accordance with the San Francisco Fair Chance Ordinance, we always consider qualified applicants with arrest and conviction records.