Staff Software Engineer, Trust & Safety

Replit; Foster City (CA); On-site; USD 180,000 - 240,000; Full time

Benefits offered by this job

Competitive Salary & Equity

401(k) Program with a 4% match (US)

Health, Dental, Vision and Life Ins

Short Term and Long Term Disability

Paid Parental, Medical, CaregiverLeave

Flexible Time Off

Commuter Benefits

Monthly Wellness Stipend

Autonomous Work Environment

In-Office Setup Reimbursement

Quarterly Team Gatherings

In-Office Amenities

Job summary

Replit's Trust & Safety team is seeking a security engineer to design and operate abuse-detection systems across millions of daily user actions.

You will build ML/LLM-based classifiers, implement guardrails for AI-generated code, and automate responses while coordinating with Support and Legal.

This role requires 8+ years in security, strong Python/TypeScript skills, and experience with BigQuery, SAST/SCA, and CI/CD security in a fast-paced platform environment.

Qualifications

• 8+ years in security engineering, anti-abuse, or fraud detection.
• Strong Python and/or TypeScript programming for detection systems.
• Experience with SQL and large-scale data analysis.
• Experience with ML/LLM-based classifiers for security.
• Familiarity with prompt injection and LLM attack vectors.
• Ability to translate findings into automated defenses.
• Clear cross-team communication.

Responsibilities

• Design and implement LLM guardrails to detect abuse in AI-generated code.
• Build AI-powered detection systems using LLMs.
• Operate abuse detection across millions of daily actions.
• Design automated response mechanisms enforcing policies.
• Own full abuse response lifecycle with Support and Legal.
• Analyze attack patterns using BigQuery and Hex.
• Maintain internal detection tools Slurper and Netwatch.
• Integrate CI pipelines with SAST/SCA scanners.
• Track abuse trends and adapt defenses.

Skills

Security engineering

Anti-abuse

Trust & Safety

Fraud detection

Python

TypeScript

SQL

Communication

Tools

Go

BigQuery

Hex

SAST/SCA scanners

CI/CD tooling

Kubernetes

GCP

Job description

Replit is the agentic software creation platform that enables anyone to build applications using natural language. With millions of users worldwide, Replit is democratizing software development by removing traditional barriers to application creation.

About The Role

The Trust & Safety team is the front line defending Replit's platform from exploitation. We detect and shut down phishing deployments, prevent cryptomining on free-tier infrastructure, stop LLM token farming, and keep bad actors from weaponizing the platform against our users. This is adversarial work: attackers adapt constantly, and we build the detection systems, heuristics, and automated responses that stay ahead of them.

In this role you will…

• Design and implement LLM guardrails that detect abuse scenarios in AI-generated code and agent interactions
• Build AI-powered detection systems that use LLMs to identify malicious patterns, classify threats, and automate response decisions
• Build and operate abuse detection systems that identify phishing, cryptomining, account takeover, and financial fraud across millions of daily user actions
• Design automated response mechanisms that enforce platform policies without manual intervention
• Own the full abuse response lifecycle: detection, investigation, enforcement, and handling appeals alongside Support and Legal
• Analyze attack patterns using BigQuery and Hex, turning investigation findings into new detection rules
• Maintain and extend internal detection tools (Slurper, Netwatch) that continuously monitor user activity
• Integrate and tune security scanners (SAST, SCA) in CI pipelines with tight performance SLAs
• Track abuse trends, measure detection effectiveness, and adapt defenses as attack patterns evolve

Required Skills And Experience

• 8+ years of experience in security engineering, anti-abuse, trust & safety, or fraud detection
• Strong programming skills in Python and/or TypeScript for building detection systems and automation
• Experience with SQL and data analysis at scale (BigQuery, Snowflake, or similar)
• 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 infrastructure, account takeover, credential stuffing, resource abuse
• Clear communication skills for working across Security, Support, Legal, and Engineering teams.

Nice To Have

• Experience at a platform company dealing with user-generated content or compute abuse (hosting providers, cloud platforms, developer tools)
• Background in fraud detection, payment abuse, or financial crime
• Familiarity with device fingerprinting, IP reputation, and email validation services
• Experience with CI/CD security tooling (SAST, SCA, Dependabot, Snyk)
• Knowledge of container security, Linux internals, or cloud infrastructure (GCP preferred)
• Prior work with abuse reporting pipelines, trust & safety tooling, or content moderation systems

Tools + Tech Stack for this role

• Languages: Python, TypeScript, Go, SQL
• Data: BigQuery, Hex
• Detection tools: Slurper, Netwatch, Stytch (device fingerprint); ClearOut (email reputation)
• CI/CD Security: Dependabot, Snyk, SAST/SCA scanners
• Infrastructure: GCP, Kubernetes
• Collaboration: Linear, Slack, Zendesk (for abuse reports)

This role may not be a fit if

• You prefer deep security research over building operational detection systems
• You want to focus on vulnerability management, pentesting, or bug bounty triage (that's our Security team)
• You're looking for a role with predictable, well-defined problems rather than constantly adapting to adversarial behavior
• You prefer working in isolation rather than partnering closely with Support, Legal, and cross-functional teams
• You're uncomfortable making enforcement decisions that affect real users

This is a full-time role that can be held from our Foster City, CA office. The role has an in-office requirement of Monday, Wednesday, and Friday.

Full-Time Employee Benefits Include

• 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)

Want to learn more about what we are up to?

• Meet the Replit Agent
• Replit: Make an app for that
• Replit Blog
• Amjad TED Talk

Interviewing + Culture at Replit

• Operating Principles
• Reasons not to work at Replit

To achieve our mission of making programming more accessible around the world, we need our team to be representative of the world. We welcome your unique perspective and experiences in shaping this product. We encourage people from all kinds of backgrounds to apply, including and especially candidates from underrepresented and non-traditional backgrounds.