Senior Software Engineer, Fraud
Remote • Foster City, CA • FullTime
Posted 2mo ago
Remote Work Policy
Fully remote
Employment Type
FullTime
Categories
Applied AI Engineer
About the job
The Fraud team at Replit is on the front lines, defending the platform from exploitation by detecting and shutting down malicious activities. This adversarial role involves building detection systems, heuristics, and automated responses to combat threats like phishing, cryptomining, LLM token farming, and platform weaponization. You will work on unique AI-native security challenges, including building guardrails for AI-generated code, detecting prompt injection attacks at scale, and leveraging LLMs for defense. This is an opportunity to gain hands-on experience applying AI to security problems in a production environment with real attackers, owning problems end-to-end from identifying abuse patterns to shipping scalable solutions.
Responsibilities
- Design and implement LLM guardrails for AI-generated code and agent interactions.
- Build AI-powered detection systems using LLMs for threat identification, classification, and automated response.
- Develop and operate abuse detection systems for phishing, cryptomining, account takeover, and financial fraud.
- Design automated response mechanisms to enforce platform policies.
- Manage the full abuse response lifecycle: detection, investigation, enforcement, and appeals.
- Analyze attack patterns using BigQuery and Hex to create new detection rules.
- Maintain and extend internal detection tools like Slurper and Netwatch.
- Integrate and tune security scanners (SAST, SCA) in CI pipelines with performance SLAs.
- Track abuse trends, measure detection effectiveness, and adapt defenses.
Requirements
- 4+ years of experience in security engineering, anti-abuse, trust & safety, or fraud detection.
- Strong programming skills in Python and/or TypeScript.
- Experience with SQL and large-scale data analysis (e.g., BigQuery, Snowflake).
- Experience building or fine-tuning ML/LLM-based classifiers for security or abuse detection.
- Familiarity with prompt injection, jailbreaking, and other LLM-specific attack vectors.
- Ability to investigate complex abuse patterns and translate findings into automated defenses.
- Familiarity with common attack patterns (phishing, account takeover, credential stuffing, resource abuse).
- Clear communication skills for cross-functional collaboration.
Benefits
- Competitive Salary & Equity
- 401(k) Program with a 4% match (US Only)
- Health, Dental, Vision and Life Insurance
- Short Term and Long Term Disability
- Paid Parental, Medical, Caregiver Leave
- Flexible Time Off (FTO) + Holidays
- Commuter Benefits (In-Office Only)
- Monthly Wellness Stipend
- Autonomous Work Environment
- In Office Set-Up Reimbursement (In-Office Only)
- Quarterly Team Gatherings
- In Office Amenities (In-Office Only)