Senior Machine Learning Engineer, Reddit
GenAI Security
$216.7-303.4k
+ Eligible to receive equity in the form of restricted stock units
Online platform for thoughts, experiences & discussions
Open for applications
Online platform for thoughts, experiences & discussions
1001+ employees
Open for applications
$216.7-303.4k
+ Eligible to receive equity in the form of restricted stock units
1001+ employees
Company mission
To empower communities, and make their knowledge accessible to all.
Role
Who you are
- 5+ years of experience building, training, evaluating, and deploying production ML or deep learning models
- Hands-on experience with modern ML frameworks such as PyTorch, TensorFlow, or similar
- Strong practical understanding of the full ML lifecycle: problem definition, data ETL, feature engineering, training, evaluation, deployment, monitoring, debugging, and retraining
- Experience building data pipelines and working with large-scale datasets
- Experience designing rigorous model evaluations, including precision/recall/F1, false positive analysis, threshold tuning, calibration, holdout sets, regression tests, and production-quality validation
- Experience shipping production-quality software, preferably in Python and/or Go
- Strong communication skills and ability to explain model behavior, risk tradeoffs, and technical decisions to cross-functional partners
- BS degree in Computer Science, Machine Learning, a related technical field, or equivalent practical experience
- Experience in the following areas is a plus:
- Applying ML to security, privacy, trust and safety, abuse prevention, adversarial ML, or GenAI security problems
- Training or fine-tuning neural text models for complex inputs such as long-context prompts, structured payloads, code-like content, multi-turn interactions, or tool calls
- Production MLOps or model serving systems such as Airflow, Ray, MLflow, Triton, ONNX, Kubernetes, or similar
- Improving model quality through labeling strategy, hard-negative mining, synthetic data generation, distillation, or active learning
What the job involves
- We are looking for a Senior Machine Learning Engineer to lead model development for GenAI Security and help establish strong ML practices across SPACE. This role owns the full machine learning lifecycle: problem definition, data ETL, feature engineering, model training, model evaluation, deployment, experimentation, prediction, monitoring, debugging, and retraining
- Build and improve security-focused ML models for Reddit’s GenAI traffic, including guardrail models, semantic classifiers, anomaly detection models, and other neural network based security signals
- Own model development end to end: define the security problem, assemble and label datasets, build ETL pipelines, engineer features, train models, evaluate quality, deploy to production, monitor performance, and retrain from production feedback
- Use modern deep learning architectures, including neural networks, transformers, sequence models, embeddings, and model distillation where they are the right practical fit
- Design rigorous evaluation suites for adversarial examples, hard negatives, long-context inputs, structured payloads, tool calls, multi-turn workflows, and real production traffic
- Improve model precision, recall, latency, cost, calibration, and operational reliability for high-impact production surfaces
- Build repeatable MLOps workflows for SPACE, including training pipelines, model lineage, artifact management, holdout evaluation, dashboards, rollback paths, and retraining loops
- Partner closely with ML Infrastructure, LLM Gateway, DevX, Ads, Answers, Safety, Privacy, Compliance, and other Security teams to bring security models into real production workflows
- Work pragmatically with Reddit’s evolving ML platform, using existing infrastructure where possible and building focused tooling when needed to keep model iteration moving
- Translate security goals into measurable model outcomes and help partners understand tradeoffs between risk reduction, latency, false positives, and product impact
- Provide technical direction to other engineers and serve as a go-to ML expert for GenAI Security and broader SPACE model needs
Our take
Reddits is an online platform that hosts thousands of message board communities (known as subreddits) designed to foster authentic human connection. With more than 130,000 communities covering everything from food, entertainment and sports, to niche interests for highly specific audiences, there's virtually a space for everyone.
The platform attracts over 120 million daily users and billions of monthly page views. While these figures are smaller than those of social media giants like Facebook and X, Reddit stands out by offering easily discoverable communities where users can dive deep into virtually any topic imaginable.
Today, Reddit continues to grow its user base and expand its reach, remaining a unique hub for conversation, connection and shared interests. With its strong community-driven model and steady revenue streams, it's most definitely positioned to stay a central part of online culture for years to come.
Kirsty
Company Specialist at Welcome to the Jungle
Insights
57% employee growth in 12 months
Company
Funding (last 2 of 6 rounds)
Aug 2021
$410m
SERIES F
Feb 2021
$250m
SERIES E
Total funding: $1.2bn
Company benefits
- Comprehensive health benefits
- Flexible vacation & Reddit global days off
- Family planning funds & 4+ months paid parental leave
- Personal & professional development funds
- Paid volunteer time off
- Workspace & home office benefits
Company HQ
SoMa, San Francisco, CA
Leadership
Steve Huffman
(CEO & Founder)After co-founding Reddit in 2005, they stepped away from the company to co-found Hipmunk, where they were the CTO for 5 years. They returned to Reddit in 2015, and have been the CEO since.
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