Reddit

Senior Machine Learning Engineer, ML Efficiency

Reddit$216K — $303K *
US-AnywhereRemote in United States
Information Technology
Less than 5 years of experience
Job Overview by Ladders

Qualifications

  • Deep experience with ML systems in production environments.
  • Proven track record in enhancing training or serving efficiency with measurable results.
  • Strong judgment on optimization at various system levels.
  • Ability to manage complex projects and collaborate cross-functionally.
  • Strong customer focus with an eye for maintainability and future use.
  • Excellent communication skills for conveying technical tradeoffs.

Responsibilities

  • Own high-impact optimization projects across Ads ML training and inference.
  • Identify and diagnose production bottlenecks using profiling and benchmarking.
  • Develop performance tools and optimization frameworks for multiple teams.
  • Enhance launch safety and efficiency through robust operational practices.
  • Collaborate with model and platform teams to implement feasible solutions.
  • Guide team direction by identifying patterns and opportunities for automation.
  • Mentor junior engineers in technical skills and effective execution.

Benefits

  • Comprehensive healthcare and income replacement programs.
  • 401k plan with employer match.
  • Global benefits aligned with your lifestyle and professional growth.
  • Family planning support available.
  • Gender-affirming care offered.
  • Mental health resources and coaching benefits.
  • Flexible vacation policy and generous paid time off for volunteering.
  • Paid parental leave for family support.
Full Job Description
About the Role

Reddit is building a dedicated Ads ML Efficiency function to make model training and inference materially faster, cheaper, safer, and more scalable. This person will be a key senior engineer on that team, owning meaningful efficiency work across training systems, inference and serving paths, launch-readiness tooling, and reusable optimization capabilities for Ads ML.

This role sits at the intersection of ML modeling, systems optimization, and engineering leverage. The engineer will partner closely with ranking teams, serving owners, and ML Platform to identify important bottlenecks, land measurable efficiency wins, and help build the mechanisms that make those wins repeatable.
What you'll do
  • Independently own high-value optimization initiatives across training, inference, or launch-readiness for important Ads ML workloads.
  • Diagnose bottlenecks in real production systems using profiling, benchmarking, and observability rather than intuition-first debugging.
  • Build performance tooling, optimization playbooks, observability hooks, guardrails, or efficiency primitives that help more than one team or workload over time.
  • Improve launch-safety and efficiency readiness by contributing to load testing, fallback readiness, latency and cost visibility, and operational confidence for heavy models.
  • Work with model owners and platform teams to land pragmatic fixes while helping the team gradually standardize repeated solutions.
  • Contribute to the team's technical direction by surfacing patterns, tradeoffs, and opportunities for reuse or automation.
  • Mentor less-experienced engineers through code, debugging, measurement rigor, and strong execution habits.
What we're looking for
  • Deep ML systems experience close to real production models and workloads, not just generic infra exposure.
  • Direct hands-on experience improving training or serving efficiency with measurable outcomes.
  • Strong technical judgment across model-level, runtime-level, and infrastructure-level optimization choices.
  • Ability to own complex projects end to end and collaborate effectively across team boundaries.
  • Good customer and platform instincts: can solve concrete bottlenecks while keeping maintainability, adoption, and future reuse in mind.
  • Strong communication: able to explain tradeoffs clearly to engineers and partner teams.
Nice-to-have
  • Experience with GPU training or serving migrations.
  • Experience with PyTorch, distributed training frameworks, or kernel/runtime optimization.
  • Experience building launch certification, efficiency benchmarking, or cost observability systems.
  • Experience in organizations where platform and applied modeling responsibilities are split across multiple teams.
  • Experience with model compression or deployment optimizations such as quantization, pruning, distillation, or checkpoint optimization.

Benefits:
  • Comprehensive Healthcare Benefits and Income Replacement Programs
  • 401k with Employer Match
  • Global Benefit programs that fit your lifestyle, from workspace to professional development to caregiving support
  • Family Planning Support
  • Gender-Affirming Care
  • Mental Health & Coaching Benefits
  • Flexible Vacation & Paid Volunteer Time Off
  • Generous Paid Parental Leave


Pay Transparency:

This job posting may span more than one career level.

In addition to base salary, this job is eligible to receive equity in the form of restricted stock units, and depending on the position offered, it may also be eligible to receive a commission. Additionally, Reddit offers a wide range of benefits to U.S.-based employees, including medical, dental, and vision insurance, 401(k) program with employer match, generous time off for vacation, and parental leave. To learn more, please visit https://www.redditinc.com/careers/.

To provide greater transparency to candidates, we share base salary ranges for all US-based job postings regardless of state. We set standard base pay ranges for all roles based on function, level, and country location, benchmarked against similar stage growth companies. Final offer amounts are determined by multiple factors including, skills, depth of work experience and relevant licenses/credentials, and may vary from the amounts listed below.

The base salary range for this position is:

$216,700-$303,400 USD

In select roles and locations, the interviews will be recorded, transcribed and summarized by artificial intelligence (AI). You will have the opportunity to opt out of recording, transcription and summarization prior to any scheduled interviews.

During the interview, we will collect the following categories of personal information: Identifiers, Professional and Employment-Related Information, Sensory Information (audio/video recording), and any other categories of personal information you choose to share with us. We will use this information to evaluate your application for employment or an independent contractor role, as applicable. We will not sell your personal information or disclose it to any third party for their marketing purposes. We will delete any recording of your interview promptly after making a hiring decision. For more information about how we will handle your personal information, including our retention of it, please refer to our Candidate Privacy Policy for Potential Employees and Contractors.

About Reddit

Reddit is an American social news aggregation, web content rating, and discussion website. Registered members submit content to the site such as links, text posts, images, and videos, which are then voted up or down by other members. Posts are organized by subject into user-created boards called "communities" or "subreddits", which cover topics such as news, politics, religion, science, movies, video games, music, books, sports, fitness, cooking, pets, and image-sharing. Submissions with more upvotes appear towards the top of their subreddit and, if they receive enough upvotes, ultimately on the site's front page. Although there are strict rules prohibiting harassment, it still occurs, and Reddit administrators moderate the communities and close or restrict them on occasion. Moderation is also conducted by community-specific moderators, who are not considered Reddit employees. As of September 2021, Reddit ranks as the 19th-most-visited website in the world and 7th most-visited website in the U.S., according to Alexa Internet. About 42–49.3% of its user base comes from the United States, followed by the United Kingdom at 7.9–8.2% and Canada at 5.2–7.8%. Twenty-two percent of U.S. adults aged 18 to 29 years, and 14 percent of U.S. adults aged 30 to 49 years, regularly use Reddit. Reddit was founded by University of Virginia roommates Steve Huffman and Alexis Ohanian, with Aaron Swartz, in 2005. Condé Nast Publications acquired the site in October 2006. In 2011, Reddit became an independent subsidiary of Condé Nast's parent company, Advance Publications. In October 2014, Reddit raised $50 million in a funding round led by Sam Altman and including investors Marc Andreessen, Peter Thiel, Ron Conway, Snoop Dogg, and Jared Leto. Their investment valued the company at $500 million then. In July 2017, Reddit raised $200 million for a $1.8 billion valuation, with Advance Publications remaining the majority stakeholder. In February 2019, a $300 million funding round led by Tencent brought the company's valuation to $3 billion. In August 2021, a $700 million funding round led by Fidelity Investments raised that valuation to over $10 billion.
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